Ion-sensitive, water-dispersible fabrics, a method of making same and items using same

ABSTRACT

The present invention is directed to ion-sensitive, water-dispersible fabric. The present invention is also directed to a method of making ion-sensitive, water-dispersible polymer formulations and their applicability as binder compositions for disposable items. The present invention is further directed to disposable items, such as wet-wipes comprising ion-sensitive, water-dispersible binder

[0001] This application is a continuation-in-part of application Ser.No. 09/564,212 entitled “ION-SENSITIVE, WATER-DISPERSIBLE POLYMERS, AMETHOD OF MAKING SAME AND ITEMS USING SAME” and filed in the U.S. Patentand Trademark Office on May 4, 2000. The entirety of this application ishereby incorporated by reference.

BACKGROUND OF THE INVENTION

[0002] For many years, the problem of disposability has plaguedindustries which provide disposable items, such as, diapers, wet wipes,incontinent garments and feminine care products. While much headway hasbeen made in addressing this problem, one of the weak links has been theinability to create an economical coherent fibrous web, which willreadily dissolve or disintegrate in water, but still have sufficientin-use strength. See, for example, U.K. Patent disclosure 2,241,373 andU.S. Pat. No. 4,186,233. Without such a product, the ability of the userto dispose of the product by flushing it down the toilet is greatlyreduced, if not eliminated. Furthermore, the ability of the product todisintegrate in a landfill is quite limited because a large portion ofthe product components, which may well be biodegradable orphotodegradable, are encapsulated in or bound together by plastic whichdegrades over a long period of time, if at all. Accordingly, if theplastic disintegrated in the presence of water, the internal componentscould degrade as a result of the rupture of the plastic encapsulation orbinding.

[0003] Disposable products, such as diapers, feminine care products andadult incontinent care products may be made to be disposed by flushingdown toilets. Usually such products comprise a body side liner whichmust rapidly pass fluids, such as urine or menses, so that the fluid maybe absorbed by an absorbent core of the product. Typically, the bodyside liner may be a coherent fibrous web, which desirably possesses anumber of characteristics, such as softness and flexibility. The fibrousweb of the body side liner material may be typically formed by wet ordry (air) laying a generally random plurality of fibers and joining themtogether to form a coherent web with a binder compositions. Past bindercompositions have performed this function well. However, fibrous webscomprising these compositions tended to be non-dispersible and presentproblems in typical household sanitation systems.

[0004] Recent binder compositions have been developed which can be moredispersible and are more environmentally responsible than past bindercompositions. One class of binder compositions includes polymericmaterials having inverse solubility in water. These binder compositionsare insoluble in warm water, but are soluble in cold water, such asfound in a toilet. It is well known that a number of polymers exhibitcloud points or inverse solubility properties in aqueous media. Thesepolymers have been cited in several publications for variousapplications, including (1) as evaporation retarders (JP 6207162); (2)as temperature sensitive compositions, which are useful as temperatureindicators due to a sharp color change associated with a correspondingtemperature change (JP 6192527); (3) as heat sensitive materials thatare opaque at a specific temperature and become transparent when cooledto below the specific temperature (JP 51003248 and JP 81035703); (4) aswound dressings with good absorbing characteristics and easy removal (JP6233809); and (5) as materials in flushable personal care products (U.S.Pat. No. 5,509,913, issued to Richard S. Yeo on Apr. 23, 1996 andassigned to Kimberly-Clark Corporation).

[0005] Other recent binders of interest include a class of binders,which are ion-sensitive. Several U.S. and European patents assigned toLion Corporation of Tokyo, Japan, disclose ion-sensitive polymerscomprising acrylic acid and alkyl or aryl acrylates. See U.S. PatentNos. 5,312,883, 5,317,063 and 5,384,189, the disclosures of which areincorporated herein by reference in their entirety, as well as, EuropeanPatent No. 608460A1. In U.S. Pat. No. 5,312,883, terpolymers aredisclosed as suitable binders for flushable nonwoven webs. The disclosedacrylic acid-based terpolymers, which comprise partially neutralizedacrylic acid, butyl acrylate and 2-ethylhexyl acrylate, are suitablebinders for use in flushable nonwoven webs in some parts of the world.However, because of the presence of a small amount of sodium acrylate inthe partially neutralized terpolymer, these binders fail to disperse inwater containing more than about 15 ppm Ca²⁺ and/or Mg²⁺. When placed inwater containing more than about 15 ppm Ca²⁺ and/or Mg²⁺ ions, nonwovenwebs using the above-described binders maintain a tensile strengthgreater than 30 g/in, which negatively affects the “dispersibility” ofthe web. The proposed mechanism for the failure is that each calcium ionbinds with two carboxylate groups either intramolecularly orintermolecularly. Intramolecular association causes the polymer chain tocoil up, which eventually leads to polymer precipitation. Intermolecularassociation yields crosslinking. Whether intramolecular orintermolecular associations are taking place, the terpolymer is notsoluble in water containing more than about 15 ppm Ca²⁺ and/or Mg²⁺. Dueto the strong interaction between calcium ions and the carboxylategroups of the terpolymer, dissociation of the complex is highlyunlikely. Therefore, the above-described polymer that has been exposedto a high Ca²⁺ and/or Mg²⁺ concentration solution will not disperse inwater even if the calcium concentration decreases. This limits theapplication of the polymer as a flushable binder material because mostareas across the U.S. have hard water, which contains more than 15 ppmCa²⁺ and/or Mg²⁺.

[0006] In a co-pending application assigned to Kimberly Clark; i.e.,U.S. patent application Ser. No. 09/223,999, filed Dec. 31, 1998 andrelated case WO/0038751, published on Jul. 6, 2000, the disclosures ofwhich are incorporated herein by reference in their entirety, there isdisclosed a modification of the acrylic acid terpolymers of theabove-referenced patents to Lion Corporation. Specifically, U.S. patentapplication Ser. No. 09/223,999 discloses a sulfonate anion modifiedacrylic acid terpolymers which has improved dispersibility in relativelyhard water; e.g., up to 200 ppm Ca²⁺ and/or Mg²⁺, compared to theunmodified Lion polymers. However, the Lion Corporation ion-sensitivepolymers of the above-referenced patents and the sulfonate anionmodified acrylic acid terpolymers of the co-pending application, whenused as binders for personal care products, such as wet wipes, typicallyhave reduced sheet wettability, increased sheet stiffness, increasedsheet stickiness, reduced binder sprayability and relatively highproduct cost.

[0007] Another approach to dispersible personal care products isdisclosed in U.S. Pat. No. 5,281,306 to Kao Corporation of Tokyo, Japan.This patent discloses a water-disintegratable cleansing sheet; i.e., wetwipe, comprising water-dispersible fibers treated with a water-solublebinder having a carboxyl group. The cleansing sheet is treated with acleansing agent containing 5%-95% of a water-compatible organic solventand 95%-5% water. A preferred organic solvent is propylene glycol. Thecleansing sheet retains wet strength and does not disperse in theorganic solvent-based cleansing agent, but disperses in water.

[0008] Although many patents disclose various ion and temperaturesensitive compositions for water-dispersible or flushable materials,there exists a need for dispersible products possessing softness,flexibility, three dimensionality, and resiliency; wicking andstructural integrity in the presence of body fluids (including feces) atbody temperature; and true fiber dispersion after toilet flushing sothat fibers do not become entangled with tree roots or at bends in sewerpipes. In addition, the known ion-sensitive polymers, such as those ofLion Corporation and the co-pending application of Kimberly Clark, haverelatively high viscosities at high shear rates that make application byspraying impossible or impractical. Moreover, there is a need in the artfor flushable products having water-dispersibility in all areas of theworld, including soft and hard water areas. Furthermore, there is a needfor water-dispersible binders that do not reduce wettability of productwith which they are used and are sprayable for easy and uniformapplication to and penetration into products. Finally, there is a needfor water-dispersible, flushable wet wipes that are stable duringstorage and retain a desired level of wet strength during use and arewetted with a wetting composition that is relatively free, or issubstantially free, of organic solvents. Such a product is needed at areasonable cost without compromising product safety and environmentalconcerns, something that past products have achieved with only limitedsuccess.

SUMMARY OF THE INVENTION

[0009] The present invention is directed to water dispersible fibrousfabrics or material compositions comprising, in part, an ion-sensitivewater-dispersible binder which has been developed to address theabove-described problems associated with currently available,ion-sensitive polymers and other polymers described in literature. Theion-sensitive compositions of the present invention include polymerformulations which have a “trigger property,” such that the polymers ofthe fabric are insoluble in a wetting composition comprising ions of aparticular type and concentration, such as monovalent salt solutions ata concentration from about 0.3% to about 10%, but can be dispersed whendiluted with water, including divalent and/or multivalent salt solutionssuch as hard water with up to 200 ppm (parts per million, by weight)calcium and magnesium ions. Unlike some ion-sensitive polymerformulations, which lose dispersibility in hard water because of ioncross-linking by calcium ions, the polymer formulations and thus thecompositions of the present invention are relatively insensitive tocalcium and/or magnesium ions. Consequently, flushable productscontaining the fabric or compositions of the present invention maintaindispersibility in hard water. Furthermore, the ion-sensitive polymerformulations of the present invention can have improved properties ofsprayability or reduced high-shear viscosity, improved productwettability or decreased properties of product stiffness and stickiness.

[0010] The products or materials of the present invention are usefulstructural components for air-laid and wet-laid nonwoven fabrics forapplications such as body-side liners, fluid distribution materials,fluid intake materials (surge) or cover stock in various personal careproducts. The flushable products maintain integrity or wet strengthduring storage and use, and break apart or disperse after disposal inthe toilet when the salt concentration falls below a critical level.Suitable substrates for treatment include, but are not limited to,tissue, such as creped or uncreped tissue, coform products,hydroentangled webs, airlaid mats, fluff pulp, nonwoven webs, andcomposites thereof. Methods for producing uncreped tissues and moldedthree-dimensional tissue webs of use in the present invention can befound in commonly owned U.S. patent application, Ser. No. 08/912,906,“Wet Resilient Webs and Disposable Articles Made Therewith,” by F. J.Chen et al., filed Aug. 15, 1997; U.S. Pat. No. 5,429,686, issued toChiu et al. on Jul. 4, 1995; U.S. Pat. No. 5,399,412, issued to S. J.Sudall and S. A. Engel on Mar. 21, 1995; U.S. Pat. No. 5,672,248, issuedto Wendt et al. on Sep. 30, 1997; and U.S. Pat. No. 5,607,551, issued toFarrington et al. on Mar. 4, 1997; all of which are herein incorporatedby reference in their entirety. The molded tissue structures of theabove patents can be especially helpful in providing good cleaning in awet wipe. Good cleaning can also be promoted by providing a degree oftexture in other substrates as well by embossing, molding, wetting andthrough-air drying on a textured fabric, and the like.

[0011] Airlaid material can be formed by metering an airflow containingthe fibers and other optional materials, in substantially dry condition,onto a typically horizontally moving wire forming screen. Suitablesystems and apparatus for air-laying mixtures of fibers andthermoplastic material are disclosed in, for example, U.S. Pat. No.4,157,724 (Persson), issued Jun. 12, 1979, and reissued Dec. 25, 1984 asRe. U.S. Pat. No. 31,775; U.S. Pat. No. 4,278,113 (Persson), issued Jul.14, 1981; U.S. Pat. No. 4,264,289 (Day), issued Apr. 28, 1981; U.S. Pat.No. 4,352,649 (Jacobsen et al.), issued Oct. 5, 1982; U.S. Pat. No.4,353,687 (Hosler, et al.), issued Oct. 12, 1982; U.S. Pat. No.4,494,278 (Kroyer, et al.), issued Jan. 22, 1985; U.S. Pat. No.4,627,806 (Johnson), issued Dec. 9, 1986; U.S. Pat. No. 4,650,409(Nistri, et al.), issued Mar. 17, 1987; and U.S. Pat. No. 4,724,980(Farley), issued Feb. 16, 1988; and U.S. Pat. No. 4,640,810 (Laursen etal.), issued Feb. 3, 1987.

[0012] The present invention also discloses how to makewater-dispersible nonwovens, including cover stock (liner), intake(surge) materials and wet wipes, which are stable in fluids having afirst ionic composition, such as monovalent ions at a particularconcentration greater than is found in typical hard water, using theabove-described unique polymer formulations as binder compositions. Theresultant nonwovens are flushable and water-dispersible due to thetailored ion sensitivity, which can be triggered regardless of thehardness of water found in toilets throughout the United States and theworld. Dispersible products in accordance with the present inventionalso can have improved properties of softness and flexibility. Suchproducts may also have reduced stickiness. In some embodiments, thepolymer formulations with which such articles are treated can haveimproved properties of sprayability, which improves polymer distributionon the product and penetration into the product, in addition to ease ofapplication, which translates into cost savings.

[0013] The present invention also discloses the unexpected benefitsobtained where less than about 20%, desirably about 10-15%, of thefibers of the fibrous substrate comprising the water-dispersible fabrichave a length of about 6 to about 10 mm, desirably about 7 to about 9mm, and most desirably about 8 mm. The present invention discloses thatwhere the fabric or composite is comprised of such percentage of fibershaving such length that a certain amount of engagement or overlapping(which may also include interweaving and/or entangling) of the fibersoccurs that unexpected strength is experienced by the fabric even in theabsence of a binder. This is especially true when the Dry TensileStrength of the material is compared to that of a material having lessengagement. This additional sheet strength allows for an increase inprocessing or line speed of the product. In turn, the increase inprocessing or line speed of the product allows for an increase in theamount of product produced, thereby contributing to increased profits.It is noted that while the engagement of the fibers provides an increasein dry sheet strength, it does not significantly affect thedispersibility of the sheet, nor does it significantly increase theincidence of tangling or roping. The present invention also providesadditional benefit in the production or manufacture of the product inthat less binder is needed to achieve and maintain the desired fabricstrength characteristics. It has been determined that the presentinvention provides for the use of less than about 25%, desirably about5-20%, more desirably about 10-15% by weight binder or glue. The use ofless binder in production provides not only for lower costs, but alsoprovides for an increase in the ability to wet the fibers of thesubstrate at higher sheet speed as well as greater dispersibility speed.

[0014] The present invention further discloses an improved wettingcomposition for wet wipes. Wet wipes employing the fabric or compositionof the present invention are stable during storage and retain a desiredlevel of wet strength during use and are wetted with a wettingcomposition or cleaning agent that can be relatively free, or issubstantially free, of organic solvents.

Definitions

[0015] As used herein the following terms have the specified meanings,unless the context demands a different meaning, or a different meaningis expressed; also, the singular generally includes the plural, and theplural generally includes the singular unless otherwise indicated.

[0016] As used herein, the term “cellulosic” is meant to include anymaterial having cellulose as a major constituent, and, desirably,comprising at least 50 percent by weight cellulose or a cellulosederivative. Thus, the term includes cotton, typical wood pulps,non-woody cellulosic fibers, cellulose acetate, cellulose triacetate,rayon, thermomechanical wood pulp, chemical wood pulp, debonded chemicalwood pulp, milkweed, or bacterial cellulose.

[0017] As used herein, the terms “comprises”, “comprising” and otherderivatives from the root term “comprise” are intended to be open-endedterms that specify the presence of any stated features, elements,integers, steps, or components, but do not preclude the presence oraddition of one or more other features, elements, integers, steps,components, or groups thereof.

[0018] As used herein, the term “denier” means a weight-per-unit-lengthof any linear material. Specifically, denier is the number of unitsweights of 0.05 grams per 450 meter length or the weight in grams of9,000 meters of the material.

[0019] As used herein, the term “fabric” means a material comprising anetwork of fibers including, but not limited to, woven or knittedmaterials, tufted or tufted-like materials, nonwoven webs, and so forth.

[0020] As used herein, the term “layer” when used in the singular canhave the dual meaning of a single element or a plurality of elements.

[0021] As used herein, the terms “lotion” or “ointment” are generallyinterchangeable and mean a formulation, powder or combination thereofcomprising skin health ingredients, or compositions which are skincompatible but which do not in and of themselves provide skin health orskin wellness benefits.

[0022] As used herein, the term “machine-direction” or MD means thedirection of a fabric in the direction in which it is produced. The term“cross-direction” or CD means the direction of a fabric generallyperpendicular to the MD.

[0023] As used herein, the term “medicament” refers to any compound orcomposition that provides a benefit or therapeutic effect upon and/or tothe skin by physical contact with the skin. This benefit or therapeuticeffect can be achieved upon initial application and/or over time withcontinued use.

[0024] As used herein the terms “nonwoven” and “nonwoven fabric” or“nonwoven web” mean a web having a structure of individual fibers,filaments or threads which are randomly arranged or interlaid in amat-like fashion (including papers), but not in an identifiable manneras in a knitted fabric. Nonwoven fabrics or webs have been formed frommany processes such as for example, air-laid processes, wet-laidprocesses, hydroentangling processes, meltblowing processes, spunbondingprocesses, staple fiber carding and bonding, and solution spinning. Thebasis weight of nonwoven fabrics is usually expressed in ounces ofmaterial per square yard (osy) or grams per square meter (gsm) and thefiber diameters or sizes useful are usually expressed in microns, denieror decitex (dtex). (Note that to convert from osy to gsm, multiply osyby 33.91).

[0025] As used herein, the term “personal care product” or “personalcare absorbent product” means diapers, training pants, swim wear,absorbent underpants, baby wipes, adult incontinence products, sanitarywipes, wet wipes, feminine hygiene products, wound dressings andbandages and other personal hygiene oriented items.

[0026] As used herein, the term “skin-care additives” representsadditives, which provide one or more benefits to the user, such as areduction in the probability of having diaper rash and/or other skindamage caused by fecal enzymes. As used herein, the tern skin-careadditives may specifically include, but is not limited to, emollients,lotions, ointments, medicaments, or topical applications.

[0027] As used herein, the term “soft water” refers to water having adivalent and/or multivalent ion content of less than about 10 ppm. Asused herein, the term “moderately hard water” refers to water having adivalent and/or multivalent ion content of from about 10 to about 50ppm. As used herein, the term “hard water” refers to water having adivalent and/or multivalent ion content of more than about 50 ppm up toabout 200 ppm.

[0028] As used herein, the term “tex” means a unit for expressing lineardensity, equal to the weight in grams of 1 kilometer (1000 meters) ofyarn, filament, fiber, or other textile strand. As used herein, the term“decitex” or “dtex” means a unit for expressing linear density, equal tothe weight in grams of 10,000 meters of yarn, filament, fiber, or othertextile strand. (Dtex/10=Tex).

[0029] As used herein, the term “topical application” means anyoverlayer type of material surface modification, including, but notlimited to any polishes, cleaning or cleansing agents, and the like, aswell as any lotions, ointments, powders or combinations thereof. Forpurposes of this application, the term “surface enhancing agent” isgenerally interchangeable with the term topical application.

[0030] These terms may be defined with additional language in theremaining portions of the specification.

BRIEF DESCRIPTION OF THE DRAWINGS

[0031]FIG. 1 representatively shows a perspective view of an example ofa stack of wet wipes according to the present invention wherein eachindividual wet wipe is arranged in a z-folded configuration.

[0032]FIG. 2 representatively shows a partially unfolded perspectiveview of one of the wet wipes representatively illustrated in FIG. 1.

[0033]FIG. 3 representatively shows a perspective view of an exemplaryembodiment of the water dispersible fabric of the present invention inroll form.

DETAILED DESCRIPTION OF THE INVENTION

[0034] In order to be effective ion-sensitive formulations suitable foruse in flushable or water-dispersible personal care products of thepresent invention, the formulations should desirably be (1) functional;i.e., maintain wet strength under controlled conditions and dissolve ordisperse rapidly in soft or hard water such as found in toilets andsinks around the world; (2) safe (not toxic); and (3) relativelyeconomical. In addition to the foregoing factors, the ion-sensitiveformulations when used as a binder composition for a non-wovensubstrate, such as a wet wipe, desirably should be (4) processable on acommercial basis; i.e., may be applied relatively quickly on a largescale basis, such as by spraying, which thereby requires that the bindercomposition have a relatively low viscosity at high shear; (5) provideacceptable levels of sheet or substrate wettability; and (6) provideimproved product feel, such as improved product flexibility and reducedstickiness. The wetting composition with which the wet wipes of thepresent invention are treated can provide some of the foregoingadvantages, and, in addition, can provide one or more of (7) improvedskin care, such as reduced skin irritation or other benefits, (8)improved tactile properties, and (9) promote good cleaning by providinga balance in use between friction and lubricity on the skin (skinglide). The ion-sensitive polymer formulations which are part of thefabrics and composition of the present invention, especially wet wipescomprising particular wetting compositions set forth below, can meetmany or all of the above criteria. Of course, it is not necessary forall of the advantages of the preferred embodiments of the presentinvention to be met to fall within the scope of the present invention.

[0035] The polymer formulations used in the present invention may beformed from a single triggerable polymer, such as an ion-sensitivepolymer, or from a combination of two or more different polymers, suchas a triggerable polymer and a co-binder. Desirably, at least onepolymer of the polymer formulations of the present invention is anion-sensitive polymer. Ion-sensitive polymers are known in the art andinclude any polymer whose water solubility varies depending on the typeand amount of ions present in water. Ion-sensitive polymers useful inthe present invention include, but are not limited to the Lion polymersdiscussed above, such as the Lion acrylic acid terpolymer, the sulfonateanion modified acrylic acid terpolymer of the co-pending applicationSer. No. 09/223,999 assigned to Kimberly Clark Worldwide, Inc.; theacrylic acid free polymers of the co-pending U.S. patent applicationSer. No. 09/565,623, also assigned to Kimberly Clark Worldwide, Inc.; aswell as, other ion- and chemical-sensitive polymers, including thepolymers of U.S. Pat. No. 6,043,317, issued Mar. 28, 2000 to Mumick etal., and also assigned to Kimberly Clark Worldwide, Inc.; thedisclosures of which are herein incorporated by reference in theirentirety.

[0036] Other known triggerable polymers include temperature-sensitiveand heat-sensitive polymers, as well as, polymers which becomedispersible in the presence of a dispersion aid added to the water of atoilet bowl or other water source, as discussed in U.S. Pat. No.5,948,710, issued Sept. 7, 1999 to Pomplun et al. and assigned toKimberly Clark Worldwide, Inc., the disclosure of which is hereinincorporated by reference in its entirety. U.S. Pat. No. 5,948,710 alsoindicates that another means for rendering a polymer degradable in wateris through the use of temperature change. Certain polymers exhibit acloud point temperature. As a result, these polymers will precipitateout of a solution at a particular temperature, which is the cloud point.These polymers can be used to form fibers, which are insoluble in waterabove a certain temperature, but which become soluble and thusdegradable in water at a lower temperature. As a result, it is possibleto select or blend a polymer and thus a fabric or composition, whichwill not degrade in body fluids, such as urine, at or near bodytemperature (37° C.) but which will degrade when placed in water attemperatures below body temperature, for example, at room temperature(23° C.). An example of such a polymer is polyvinylmethylether, whichhas a cloud point of 34° C. When this polymer is exposed to body fluidssuch as urine at 37° C., it will not degrade as this temperature isabove its cloud point (34° C.). However, if the polymer is placed inwater at room temperature (23° C.), the polymer will, with time, go backinto solution as it is now exposed to water at a temperature below itscloud point. Consequently, the polymer will begin to degrade. Blends ofpolyvinylmethylether and copolymers may be considered as well. Othercold water soluble polymers include poly(vinyl alcohol) graft copolymerssupplied by the Nippon Synthetic Chemical Company, Ltd. of Osaka, Japan,which are coded Ecomaty AX2000, AX10000 and AX300G.

[0037] Ion-Sensitive Polymers

[0038] The ion-sensitive Lion polymers and the ion-sensitive polymers ofthe above-referenced co-pending applications and U.S. patents ofKimberly-Clark Worldwide, Inc. are useful in the present invention. Thesulfonate anion modified acrylic acid terpolymers of co-pending patentapplication Ser. No. 09/223,999, assigned to Kimberly-Clark Worldwide,Inc., are desired because, unlike the Lion Corporation polymers andother polymers cited in technical literature, the polymers of theco-pending application Ser. No. 09/223,999 are soluble in water havingfrom less than about 10 ppm Ca²⁺ and/or Mg²⁺ up to about 200 ppm Ca²⁺and/or Mg²⁺. The polymers of the co-pending application are formulatedto minimize the potentially strong interaction between the anions of thepolymers and the cations in the water. This strong interaction can beexplained via the hard-soft acid-base theory proposed by R. G. Pearsonin the Journal of the American Chemical Society, vol. 85, pg. 3533(1963); or N. S. Isaacs in the textbook, Physical Organic Chemistry,published by Longman Scientific and Technical with John Wiley & Sons,Inc., New York (1987). Hard anions and hard cations interact stronglywith one another. Soft anions and soft cations also interact stronglywith one another. However, soft anions and hard cations, and vice-versa,interact weakly with one another. In the Lion polymers, the carboxylateanion of the sodium acrylate is a hard anion, which interacts stronglywith the hard cations, Ca²⁺ and/or Mg²⁺, present in moderately hard andhard water. By replacing the carboxylate anions with a softer anion,such as a sulfonate anion, the interaction between the anions of anion-triggerable polymer and the hard cations, Ca²⁺ and/or Mg²⁺, presentin moderately hard and hard water, is reduced.

[0039] By controlling the hydrophobic/hydrophilic balance and thecomposition of the polymers as well as the combination of polymersforming the formulation, the ion-sensitive polymer formulations havingdesired in-use binding strength and water-dispersibility in water areproduced. The ion-sensitive polymer can be a copolymer, such as aterpolymer.

[0040] Ion-sensitive acrylic acid copolymers of the present inventionmay comprise any combination of acrylic acid monomers and acrylic ester(alkyl acrylate) monomers capable of free radical polymerization into acopolymer and, specifically, a terpolymer. Suitable acrylic acidmonomers include, but are not limited to, acrylic acid and methacrylicacid. Suitable acrylic monomers include, but are not limited to, acrylicesters and methacrylic esters having an alkyl group of 1 to 18 carbonatoms or a cycloalkyl group of 3 to 18 carbon atoms and it is preferredthat acrylic esters and/or methacrylic esters having an alkyl group of 1to 12 carbon atoms or a cycloalkyl group of 3 to 12 carbon atoms be usedsingly or in combination. Other suitable monomers include, but are notlimited to, acrylamide and methacrylamide based monomers, such asacrylamide, N,N-dimethyl acrylamide, N-ethyl acrylamide, N-isopropylacrylamide, and hydroxymethyl acrylamide; N-vinylpyrrolidinone;N-vinylforamide; hydroxyalkyl acrylates and hydroxyalkyl methacrylates,such as hydroxyethyl methacrylate and hydroxyethyl acrylate. Othersuitable acrylic acid monomers and acrylic ester monomers are disclosedin U.S. Pat. No. 5,317,063, assigned to Lion Corporation, Tokyo, Japan,the disclosure of which is incorporated herein by reference in itsentirety. A particularly preferred acrylic acid terpolymer is LIONSSB-3b, available from Lion Corporation. (In alternative embodiments,the binder is formed from ion-sensitive polymers formed from monomersother than acrylic acid or its derivatives, or is relatively free ofacrylic acid, methacrylic acid, and salts thereof.)

[0041] The relative amounts of the monomers in the acrylic acidcopolymer of the present invention may vary depending on the desiredproperties in the resulting polymer. The mole percent of acrylic acidmonomer in the copolymer maybe up to about 70 mole percent. Moredesirably, the mole percent of acrylic acid monomer in the copolymermaybe from about 15 to about 70 mole percent. Most desirably, the molepercent of acrylic acid monomer in the copolymer maybe from about 40 toabout 65 mole percent.

[0042] More desirably, examples of the acrylic acid copolymers useful inthe present invention may include copolymers of about 10 weight percentto about 90 weight percent, desirably about 20 weight percent to about70 weight percent of acrylic acid and/or methacrylic acid and about 90weight percent to about 10 weight percent, desirably about 80 weightpercent to about 30 weight percent of acrylic esters and/or methacrylicesters having an alkyl group of 1 to 18 carbon atoms or a cycloalkylgroup of 3 to 18 carbon atoms in which about 1 to about 60 mole percent,desirably about 5 to about 50 mole percent of acrylic acid and/ormethacrylic acid is neutralized to form a salt; or copolymers of about30 weight percent to about 80 weight percent, desirably about 40 weightpercent to about 65 weight percent of acrylic acid, about 5 weightpercent to about 30 weight percent, desirably about 10 weight percent toabout 25 weight percent of acrylic esters and/or methacrylic estershaving an alkyl group of 8 to 12 carbon atoms and about 20 weightpercent to about 40 weight percent; desirably about 20 weight percent toabout 35 weight percent of acrylic esters and/or methacrylic estershaving an alkyl group of 2 to 4 carbon atoms in which about 1 to about50 mole percent, desirably about 2 to about 40 mole percent of acrylicacid is neutralized to form a salt.

[0043] The acrylic acid copolymers of the present invention may have anaverage molecular weight, which varies depending on the ultimate use ofthe polymer. The acrylic acid copolymers of the present inventiondesirably have a weight average molecular weight ranging from about10,000 to about 5,000,000. More desirably, the acrylic acid copolymersof the present invention have a weight average molecular weight rangingfrom about 25,000 to about 2,000,000, or, more desirably still, fromabout 200,000 to about 1,000,000.

[0044] The acrylic acid copolymers of the present invention may beprepared according to a variety of polymerization methods, desirably asolution polymerization method. Suitable solvents for the polymerizationmethod include, but are not limited to, lower alcohols such as methanol,ethanol and propanol; a mixed solvent of water and one or more loweralcohols mentioned above; and a mixed solvent of water and one or morelower ketones such as acetone or methyl ethyl ketone.

[0045] In the polymerization methods of the present invention, anysuitable polymerization initiator may be used. Selection of a particularinitiator may depend on a number of factors including, but not limitedto, the polymerization temperature, the solvent, and the monomers used.Suitable polymerization initiators for use in the present inventioninclude, but are not limited to, 2,2′-azobisisobutyronitrile,2,2′-azobis(2-methylbutyronitrile),2,2′-azobis(2,4-dimethylvaleronitrile),2,2′-azobis(2-amidinopropane)dihydrochloride,2,2′-azobis(N,N′-dimethyleneisobutylamidine), potassium persulfate,ammonium persulfate, and aqueous hydrogen peroxide. The amount ofpolymerization initiator may desirably range from about 0.01 to about 5weight percent based on the total weight of monomer present.

[0046] The polymerization temperature may vary depending on thepolymerization solvent, monomers, and initiator used, but in general,ranges from about 20° C. to about 90° C. Polymerization time generallyranges from about 2 to about 8 hours.

[0047] The sulfonate anion modified acrylic acid copolymers inaccordance with the present invention include hydrophilic monomers, suchas acrylic acid or methacrylic acid, incorporated into the acrylic acidcopolymers of the present invention along with one or moresulfonate-containing monomers. The sulfonate anions of these monomersare softer than carboxylate anions since the negative charge of thesulfonate anion is delocalized over three oxygen atoms and a largersulfur atom, as opposed to only two oxygen atoms and a smaller carbonatom in the carboxylate anion. These monomers, containing the softersulfonate anion, are less interactive with divalent and/or multivalentions present in hard water, particularly Ca²⁺ and Mg²⁺ ions. Suitablesulfonate-containing monomers include, but are not limited to,2-acrylamido-2-methyl-1-propanesulfonic acid (AMPS) and organic orinorganic salts of AMPS, such as alkali earth metal and organic aminesalts of AMPS, particularly the sodium salt of AMPS (NaAMPS). Additionalsuitable sulfonate-containing monomers include, but are not limited to,2-methyl-2-propene sulfonic acid, vinyl sulfonic acid, styrene sulfonicacid, 2-sulfopropyl methacrylate and 3-sulfopropyl acrylate, and organicor inorganic salts thereof, such as alkali earth metals and organicamine salts, such as alkyl ammonium hydroxide wherein the alkyl groupsare C₁-C₁₈. To maintain the hydrophobic/hydrophilic balance of theion-sensitive polymer, one or more hydrophobic monomers are added to thepolymer.

[0048] The ion-sensitive sulfonate anion modified acrylic acidcopolymers of the present invention may be produced from monomersincluding the following monomers: acrylic acid, methacrylic acid, or acombination thereof; AMPS and organic or inorganic salts thereof, suchas the sodium salt thereof (NaAMPS); butyl acrylate; and 2-ethylhexylacrylate. Desirably, the ion-sensitive sulfonate anion modified acrylicacid copolymers of the present invention are produced from: acrylicacid; AMPS, NaAMPS or a combination thereof; butyl acrylate; and2-ethylhexyl acrylate. Desirably, the monomers are present in thesulfonate anion modified acrylic acid copolymer at the following molepercents: acrylic acid, about 35 to less than about 80 mole percent;AMPS or NaAMPS, greater than 0 to about 20 mole percent; butyl acrylate,from greater than 0 to about 65 mole percent; and 2-ethylhexyl acrylate,from greater than 0 to about 45 mole percent. More desirably, themonomers are present in the sulfonate anion modified acrylic acidcopolymer at the following mole percents: acrylic acid, about 50 toabout 67 mole percent; AMPS or NaAMPS, from greater than 0 to about 10mole percent; butyl acrylate, from about 15 to about 28 mole percent;and 2-ethylhexyl acrylate, from about 7 to about 15 mole percent. Mostdesirably, the monomers are present in the sulfonate anion modifiedacrylic acid copolymer at the following mole percents: acrylic acid,about 57 to about 66 mole percent; AMPS or NaAMPS, from about 1 to about6 mole percent; butyl acrylate, from about 15 to about 28 mole percent;and 2-ethylhexyl acrylate, from about 7 to about 13 mole percent;especially, about 60 mole percent acrylic acid, about 5 mole percentAMPS or NaAMPS, about 24.5 mole percent butyl acrylate and about 10.5mole percent 2-ethylhexyl acrylate.

[0049] If AMPS is used as one of the monomers, it is desired toneutralize at least a portion of the acid component. Any inorganic baseor organic base may be used as a neutralizing agent to neutralize theacid component. Examples of neutralizing agents include, but are notlimited to, inorganic bases, such as sodium hydroxide, potassiumhydroxide, lithium hydroxide and sodium carbonate, and amines, such asmonoethanolamine, diethanolamine, diethylaminoethanol, ammonia,trimethylamine, triethylamine, tripropylamine, morpholine. Preferredneutralizing agents include sodium hydroxide, potassium hydroxide, or acombination thereof.

[0050] A sulfonate modified copolymer having salt-sensitivity may alsobe produced by sulfonation of an existing polymer, such as a copolymeror acrylic acid-derived terpolymer. Methods of sulfonating polymers arewell known in the art. Methods for the production of sulfonated orsulfated polymers are disclosed in U.S. Pat. No. 3,624,069, issuedNovember 1971 to Schwelger; U.S. Pat. No. 4,419,403, issued Dec. 6, 1983to Varona; U.S. Pat. No. 5,522,967, issued Jun. 4, 1996 to Shet; U.S.Pat. No. 4,220,739, issued Sep. 2, 1980 to Walles, U.S. Pat. No.5,783,200, issued Jul. 21, 1998 to Motley et al., as well as thefollowing patents: U.S. Pat. Nos. 2,400,720; 2,937,066; 2,786,780;2,832,696; 3,613,957, and 3,740,258, all of which are hereinincorporated by reference in their entirety. Principles for sulfationand sulfonation (e.g., via sulfamic acid treatment, reaction withthionyl chloride or chlorosulfonic acid, or exposure to sulfur trioxide)are among the pathways disclosed by Samuel Shore and D. R. Berger in“Alcohol and Ether Alcohol Sulfates,” in Anionic Surfactants, Part 1,ed. Warner M. Linfield, New York: Marcel Dekker, Inc., 1976, pp.135-149; and by Ben E. Edwards, “The Mechanisms of Sulfonation andSulfation,” in Anionic Surfactants, Part 1, ed. Warner M. Linfield, NewYork: Marcel Dekker, Inc., 1976, pp. 111-134, both of which are hereinincorporated by reference in their entirety.

[0051] In a further embodiment of the present invention, theabove-described ion-sensitive polymer formulations are used as bindermaterials for flushable and/or non-flushable products. In order to beeffective as a binder material in flushable products throughout theUnited States, the ion-sensitive polymer formulations of the presentinvention remain stable and maintain their integrity while dry or inrelatively low concentrations of monovalent ions, but become dispersiblein water containing up to about 200 ppm divalent and/or multivalentions, especially calcium and magnesium ions. Desirably, theion-sensitive polymer formulations of the present invention includingacrylic acid copolymers are insoluble in a salt solution containing atleast about 0.3 weight percent of one or more inorganic and/or organicsalts containing monovalent ions. More desirably, the ion-sensitivepolymer formulations of the present invention including acrylic acidcopolymers are insoluble in a salt solution containing from about 0.3weight percent to about 5 weight percent of one or more inorganic and/ororganic salts containing monovalent ions. Even more desirably, theion-sensitive polymer formulations of the present invention includingacrylic acid copolymers are insoluble in salt solutions containing fromabout 0.3 weight percent to about 4 weight percent of one or moreinorganic and/or organic salts containing monovalent ions. Suitablemonovalent ions include, but are not limited to, Na⁺ ions, K⁺ ions, Li⁺ions, NH₄ ⁺ ions, low molecular weight quaternary ammonium compounds(e.g., those having fewer than 5 carbons on any side group), and acombination thereof.

[0052] In an alternate embodiment, the ion-sensitive polymerformulations of the present invention including sulfonate anion modifiedacrylic acid copolymers may be insoluble in a salt solution containingat least about 0.3 weight percent of one or more inorganic and/ororganic salts containing monovalent ions. More desirably, theion-sensitive polymer formulations of the present invention includingsulfonate anion modified acrylic acid terpolymers are insoluble in asalt solution containing from about 0.3 weight percent to about 5 weightpercent of one or more inorganic and/or organic salts containingmonovalent ions. Even more desirably, the ion-sensitive polymerformulations of the present invention including sulfonate anion modifiedacrylic acid terpolymers are insoluble in salt solutions containing fromabout 0.3 weight percent to about 4 weight percent of one or moreinorganic and/or organic salts containing monovalent ions. Suitablemonovalent ions include, but are not limited to, Na⁺ ions, K⁺ ions, Li⁺ions, NH₄ ⁺ ions, low molecular weight quaternary ammonium compounds(e.g., those having fewer than 5 carbons on any side group), and acombination thereof.

[0053] Based on a recent study conducted by the American ChemicalSociety, water hardness across the United States varies greatly, withCaCO₃ concentration ranging from near zero for soft water to about 500ppm CaCO₃ (about 200 ppm Ca²⁺ ion) for very hard water. To ensurepolymer formulation dispersibility across the country (and throughoutthe whole world), the ion-sensitive polymer formulations of the presentinvention are desirably dispersible in water containing up to about 50ppm Ca²⁺ and/or Mg²⁺ ions. More desirably, the ion-sensitive polymerformulations of the present invention are dispersible in watercontaining up to about 100 ppm Ca²⁺ and/or Mg²⁺ ions. Even moredesirably still, the ion-sensitive polymer formulations of the presentinvention are dispersible in water containing up to about 150 ppm Ca²⁺and/or Mg²⁺ ions. Even more desirably still, the ion-sensitive polymerformulations of the present invention are dispersible in watercontaining up to about 200 ppm Ca²⁺ and/or Mg²⁺ ions.

[0054] A wide variety of polymer/surfactant systems may be used toprovide the same functionality as the ion-sensitive Lion polymers andthe ion-sensitive sulfonate anion modified acrylic acid terpolymers ofco-pending patent application Ser. No. 09/223,999, without the need tobe limited to sulfonic or carboxylic moieties. Such other systems aredescribed below.

[0055] Phosphorylated polymers containing phosphonic groups,thiophsulphonic groups, or other organophosphorous groups as the “soft”anion capable of establishing a mismatch with Ca²⁺ may be used as theion-sensitive polymer in the present invention. This can includemodified cellulose or cellulose derivatives and related gums, madeinsoluble by the presence of monovalent salts or other electrolytes. Inone embodiment, soluble cellulose derivatives, such as CMC, arephosphorylated and rendered insoluble and can be effective asion-sensitive polymer formulations when in a solution of high ionicstrength or of appropriate pH, but are dispersible in tap water. Inanother embodiment, aminophosphinic groups which can be anionic oramphoteric, are added to a polymer. Aminophosphinic groups can be addedvia condensation of a hypophosphite salt with a primary amine. Reactionof chloromethylphosphinic acid with amines can also yield useful anionicgroups, as described by Guenther W. Wasow in “Phosphorous-ContainingAnionic Surfactants,” Anionic Surfactants: Organic Chemistry, ed. HelmutW. Stache, New York: Marcel Dekker, 1996, pp. 589-590. The entirechapter by Wasow, comprising pages 551-629 of the aforementioned book,offers additional teachings relevant to creating polymers with usefulphosphorous groups, and is herein incorporated by reference.

[0056] Other methods of preparing phosphorylated cellulose fibers arewell known. These methods may be adapted to CMC, which may then serve asa binder agent. Exemplary methods are disclosed in U.S. Pat. No.3,739,782, issued Jun. 19, 1973 to Bernardin. Cellulose and synthetic ornatural polymers modified to have other “soft” anionic groups can beuseful as the ion-sensitive polymer of the present invention.

[0057] Natural polymers that are already provided with useful anionicgroups also can be useful in the present invention. Such polymersinclude agar and carageenan, which have multiple ester sulfate groups.These may be further modified, if necessary, to have additional anionicgroups (e.g., sulfonation, phosphorylation, and the like).

[0058] Polymers having two or more differing soft anionic groups, suchas both sulfonic and phosphonic groups, wherein the relative amounts ofthe differing anions can be adjusted to optimize the strength, the ionicsensitivity, and the dispersibility of the polymer, are also useful inthe present invention. This also includes zwitterionic and amphotericcompounds. Polyampholytes in particular can be readily soluble above orbelow the isoelectric point, but insoluble at the isoelectric point,offering the potential for a triggering mechanism based on electrolyteconcentration and pH. Examples of polyampholytes include, but are notlimited to, copolymers of methacrylic acid and allylamine, copolymers ofmethacrylic acid and 2-vinylpyridine, polysiloxane ionomers with pendantamphoteric groups, and polymers formed directly from zwitterionicmonomeric salts, such as the ion-pair of co-monomers (IPC) of Salamoneet al., all as disclosed by Irja Piirma in Polymeric Surfactants, NewYork: Marcel Dekker, Inc., 1992, at pp. 251-254, incorporated herein byreference.

[0059] Proteins capable of being salted out, optionally modified to haveadditional soft ionic groups, can be useful as the ion-sensitive polymerof the present invention.

[0060] Systems such as those comprising algin derivatives or naturalsulfonated polymers in which calcium ions are present in highconcentrations (much higher than the levels of about 250 ppm or lessthat may be encountered in hard water) insolubilize the binder, butallow even hard water to sufficiently dilute the calcium ion to renderthe binder dispersible are useful in the present invention. Thus, whileit is desired that the ion-sensitive binders of the present invention beinsoluble in solutions comprising a monovalent metal ion above acritical concentration, in some embodiments useful ion-sensitive bindersare insoluble in solutions comprising a divalent and/or multivalentmetal ion above a critical concentration, but become soluble when thedivalent and/or multivalent metal ion concentration falls to about 200ppm or more specifically to about 100 ppm, such that a fibrous substratewith the ion-sensitive polymer as a binder maintains good wet strengthin a solution comprising an elevated concentration of the divalentand/or multivalent metal ion, yet becomes water dispersible in hardwater or medium hard water. Thus, the triggering mechanism, whichresults in a pre-moistened wipe losing wet strength and becomingflushable even in hard water, can be due to the dilution of a monovalentor divalent and/or multivalent metal ion, and particularly an alkalimetal ion, with monovalent ions, such as sodium being preferred. Naturalpolymers and gums, which may be adapted for use as ion-sensitivebinders, are described by R. L. Whistler and J. N. BeMiller inIndustrial Gums, New York: Academic Press, Inc., 1973, incorporatedherein by reference. Natural polymers, which become firm or form a gelin the presence of calcium ions, are described below.

[0061] Algin (which may need to be in the form of sodium alginate andcalcium alginate for good dispersibility, based on reported behavior inuse as a binder for medicinal tablets—see p. 62 of Whistler andBeMiller), which is insoluble as alginic acid, calcium alginate, or ingeneral as a salt of most polyvalent metals, but soluble as sodiumalginate or as a salt with low-molecular-weight amines or quaternaryammonium compounds (See, Id. at p. 67) may be useful in the presentinvention. This material may be used, especially when zinc is aninsolubilizing metal ion.

[0062] Other useful polymers include carageenan and iridophycan, bothseaweed derivatives comprising ester sulfates.

[0063] Both natural polymers, including cellulose, and syntheticpolymers can be provided with anionic groups, such as sulfonic groups,phosphonic groups, and carboxyl groups, capable of forming bridges toother molecules in the presence of ions of a suitable type andconcentration. When the ionic concentration is substantially changed,such as by placing a cleansing article of the present invention in atoilet bowl, the article may become weak and disintegrate.

[0064] Ion-sensitive polymers include those which are dispersible inaqueous environment under prescribed conditions, yet are not dispersiblein all aqueous environments. Examples include materials that arealkaline dispersible or saline insoluble. The Eastman AQ copolyesters(available from Eastman Chemical Company, Kingsport, Tenn.), forexample, can be dispersible in deionized water yet insoluble in salinesolutions. They have been proposed for use in articles such as diapersintended to absorb body fluids. Further information on those polymers isprovided in European Patent Application 773,315-B1, “Nonwoven WebComprising Water Soluble Polyamides and Articles Constructed Therefrom,”issued May 10, 2000 by S. U. Ahmed, the disclosure of which is hereinincorporated by reference in its entirety.

[0065] Useful polyampholytes include polyacrylamide-based copolymerswhich are highly sensitive to sodium chloride concentration.

[0066] U.S. Pat. No. 3,939,836, the disclosure of which is incorporatedherein by reference in its entirety, describes an alkali salt of asulfated cellulose ester resin which gives good dry tensile strength tofabrics, which strength is retained in significant part when suchfabrics are contacted with a salt solution typical of body fluids suchas blood, menstrual fluid or urine and yet are readily dispersible inwater. The resins have a degree of sulfate substitution of from 0.10 to0.45. In U.S. Pat. No. 4,419,403, the disclosure of which isincorporated herein by reference in its entirety, colloidal sulfateesters of cellulose are used for effective water-dispersible binders,wherein the binders have a much higher degree of sulfate substitutionthan the '836 patent. The binders of the '403 patent form gels in thepresence of potassium ions. Other patents related to dispersiblepolymers and wet wipes include U.S. Pat. Nos. 4,117,187; 5,417,977;4,309,469; 5,317,063; 5,312,883; 5,384,189; 5,543,488; 5,571,876;5,709,940; 5,718,790, the disclosures of which are incorporated hereinby reference in their entirety.

[0067] Co-binder Polymers

[0068] As stated above, the polymer formulations of the presentinvention may be formed from a single ion-sensitive polymer or acombination of two or more different polymers, wherein at least onepolymer is an ion-sensitive polymer. The second polymer may be aco-binder polymer. A co-binder polymer is of a type and in an amountsuch that when combined with the ion-sensitive polymer, the co-binderpolymer desirably is largely dispersed in the ion-sensitive polymer;i.e., the ion-sensitive polymer is desirably the continuous phase andthe co-binder polymer is desirably the discontinuous phase. Desirably,the co-binder polymer can also meet several additional criteria. Forexample, the co-binder polymer can have a glass transition temperature;i.e., T_(g), that is lower than the glass transition temperature of theion-sensitive polymer. Furthermore or alternatively, the co-binderpolymer can be insoluble in water, or can reduce the shear viscosity ofthe ion-sensitive polymer. The co-binder can be present at a levelrelative to the solids mass of the triggerable polymer of about 45% orless, desirably about 35% or less, more desirably about 25% or less. Theamount of co-binder present should be low enough, for co-binders withthe potential to form water insoluble bonds or films; that the co-binderremains a discontinuous phase unable to create enough crosslinked, orinsoluble bonds, to jeopardize the dispersibility of the treatedsubstrate. In one embodiment, the ion-sensitive polymer formulation ofthe present invention can comprise about 75 weight percent acrylic acidterpolymer and about 25 weight percent poly(ethylene-vinyl acetate)co-binder.

[0069] Desirably, but not necessarily, the co-binder polymer whencombined with the ion-sensitive polymer will reduce the shear viscosityof the ion-sensitive polymer to such an extent that the combination ofthe ion-sensitive polymer and the co-binder polymer is sprayable. Bysprayable it is meant that the polymer can be applied to a nonwovenfibrous substrate by spraying and the distribution of the polymer acrossthe substrate and the penetration of the polymer into the substrate aresuch that the polymer formulation is generally capable of beinguniformly applied to the substrate.

[0070] The co-binder polymer can be in the form of an emulsion latex.The surfactant system used in such a latex emulsion should be such thatit does not substantially interfere with the dispersibility of theion-sensitive polymer.

[0071] In some embodiments, the combination of the ion-sensitive polymerand the co-binder polymer reduces the stiffness of the article to whichit is applied compared to the article with just the ion-sensitivepolymer. It has been found that when the ion-sensitive polymer, such asa sulfonate anion modified acrylic acid terpolymer, is applied to anonwoven substrate, such as an air laid layer of wood pulp, for thepurpose of forming a wet wipe, the nonwoven sheet can have anundesirable amount of stiffness that is detrimental to the dry productfeel or to the handling of the dry web during processing, when thebrittleness of the dry substrate can harm runnability. By combining theion-sensitive polymer and the co-binder polymer, the stiffness of sucharticles can be reduced. The co-binder polymer average molecular weight,varies depending on the ultimate use of the polymer. Desirably, theco-binder polymer has a weight average molecular weight ranging fromabout 500,000 to about 200,000,000. More desirably, the co-binderpolymer has a weight average molecular weight ranging from about 500,000to about 100,000,000.

[0072] Co-binder polymers that can meet many or all of the foregoingcriteria include, but are not limited to, poly(ethylene-vinyl acetate),poly(styrene-butadiene), poly(styrene-acrylic), a vinyl acrylicterpolymer, neoprene, a polyester latex, an acrylic emulsion latex, polyvinyl chloride, ethylene-vinyl chloride copolymer, a carboxylated vinylacetate latex, and the like, all of which can be non-crosslinking (e.g.,devoid of N-methylol acrylamide or other crosslinkers), crosslinking, orpotentially crosslinking (i.e., prepared with a crosslinker present) butnot substantially crosslinked in the final product.

[0073] A particularly preferred non-crosslinking poly(ethylene-vinylacetate) is Dur-O-Set® RB available from National Starch and ChemicalCo., Bridgewater, N.J. A particularly preferred non-crosslinkingpoly(styrene-butadiene) is Rovene® 4817 available from Mallard CreekPolymers, Charlotte, N.C. A particularly preferred non-crosslinkingpoly(styrene-acrylic) is Rhoplex® NM 1715K available from Rohm and Haas,Philadelphia, Pa.

[0074] When a latex co-binder, or any potentially crosslinkableco-binder is used, the latex should be prevented from formingsubstantial water-insoluble bonds that bind the fibrous substratetogether and interfere with the dispersibility of the article. Thus, thelatex can be free of crosslinking agents, such as NMA, or free ofcatalyst for the crosslinker, or both. Alternatively, an inhibitor canbe added that interferes with the crosslinker or with the catalyst suchthat crosslinking is impaired even when the article is heated to normalcrosslinking temperatures. Such inhibitors can include, but are notlimited to, free radical scavengers, methyl hydroquinone,t-butylcatechol, pH control agents such as potassium hydroxide, and thelike. For some latex crosslinkers, such as N-methylol-acrylamide (NMA),elevated pH such as a pH of 8 or higher can interfere with crosslinkingat normal crosslinking temperatures (e.g., about 130° C. or higher).Also alternatively, an article comprising a latex co-binder can bemaintained at temperatures below the temperature range at whichcrosslinking takes place, such that the presence of a crosslinker doesnot lead to crosslinking, or such that the degree of crosslinkingremains sufficiently low that the dispersibility of the article is notjeopardized. Also alternatively, the amount of crosslinkable latex canbe kept below a threshold level such that even with crosslinking, thearticle remains dispersible. For example, a small quantity ofcrosslinkable latex dispersed as discrete particles in an ion-sensitivebinder can permit dispersibility even when fully crosslinked. For thelater embodiment, the amount of latex can be below about weight percent,and, more desirably, below about 15 weight percent relative to theion-sensitive binder.

[0075] Latex compounds, whether crosslinkable or not, need not be theco-binder. Scanning Election Microscope (SEM) micrography of successfulion-sensitive binder films with useful non-crosslinking latex emulsionsdispersed therein has shown that the latex co-binder particles canremain as discrete entities in the ion-sensitive binder, possiblyserving, in part, as filler material. It is believed that othermaterials could serve a similar role, including a dispersed mineral orparticulate filler in the ion-sensitive binder, optionally comprisingadded surfactants/dispersants. For example, in one envisionedembodiment, freeflowing Ganzpearl PS-8F particles from Presperse, Inc.(Piscataway, N.J.), a styrene/divinylbenzene copolymer with about 0.4micron particles, can be dispersed in an ion-sensitive binder at a levelof about 2 to about 10 weight percent to modify the mechanical, tactile,and optical properties of the ion-sensitive binder. Other filler-likeapproaches could include microparticles, microspheres, or microbeads ofmetal, glass, carbon, mineral, quartz, and/or plastic, such as acrylicor phenolic, and hollow particles having inert gaseous atmospheressealed within their interiors. Examples include EXPANCEL phenolicmicrospheres from Expancel of Sweden, which expand substantially whenheated, or the acrylic microspheres known as PM 6545 available from PQCorporation of Pennsylvania. Foaming agents, including CO₂ dissolved inthe ion-sensitive binder, can also provide helpful discontinuities asgas bubbles in the matrix of an ion-sensitive binder, allowing thedispersed gas phase in the ion-sensitive binder to serve as theco-binder. In general, any compatible material that is not miscible withthe binder, especially one with adhesive or binding properties of itsown, can be used as the co-binder, if it is not provided in a state thatimparts substantial covalent bonds joining fibers in a way thatinterferes with the water-dispersibility of the product. However, thosematerials that also provide additional benefits, such as reduced sprayviscosity, can be especially preferred. Adhesive co-binders, such aslatex that do not contain crosslinkers or contain reduced amounts ofcrosslinkers, have been found to be especially helpful in providing goodresults over a wide range of processing conditions, including drying atelevated temperatures.

[0076] As stated above, the T_(a) of the co-binder polymer can be lowerthan the T_(g) of the ion-sensitive polymer, which is believed toimprove the flexibility of the treated substrate, especially in the drystate. Table 1 shows a comparison of the glass transition temperature ofsome of the preferred polymers useful in the present invention. TABLE 1Glass Transition Temperatures T_(g) For Select Polymers Polymer GlassTransition Temperature - T_(g) Sulfonate anion modified acrylic   55° C.acid terpolymer (dry) Sulfonate anion modified acrylic −22° C. acidterpolymer (wet) Rhoplex ® NW 1715K (dry)  −6° C. Rovene ® 4817 (dry) −4° C. Elite 33 (dry)   10° C. Elite 22 (dry) −15° C.

[0077] In an alternate embodiment, the ion-sensitive polymer formulationof the present invention comprises about 55 to about 95 weight percentsulfonate anion modified acrylic acid terpolymer and about 5 to about 45weight percent poly(ethylene-vinyl acetate). More desirably, theion-sensitive polymer formulation of the present invention comprisesabout 75 weight percent sulfonate anion modified acrylic acid terpolymerand about 25 weight percent poly(ethylene-vinyl acetate).

[0078] As stated above, useful co-binder polymers can include a varietyof commercial latex emulsions, including those selected from the Rovene®series (styrene butadiene latices available from Mallard Creek Polymersof Charlotte, N.C.), the Rhoplex® latices of Rohm and Haas Company, andthe Elite® latices of National Starch. Polymer emulsions or dispersionsgenerally comprise small polymer particles, such as crosslinkableethylene vinyl acetate copolymers, typically in spherical form,dispersed in water and stabilized with surface active ingredients suchas low molecular weight emulsifiers or high molecular weight protectivecolloids. These liquid binders can be applied to airlaid webs or othersubstrates by methods known in the art of binder treatment for nonwovenwebs, including spray or foam application, flooded nip impregnation,curtain coating, etc., followed by drying. In general, a wide variety oflatex compounds and other resins or emulsions can be considered,including vinyl, but not limited to, acetate copolymer latices, such as76 RES 7800 from Union Oil Chemicals Divisions and Resyn® 25-1103,Resyn® 25-1109, Resyn® 25-1119, and Resyn® 25-1189 from National Starchand Chemical Corporation, ethylene-vinyl acetate copolymer emulsions,such as Airflex® ethylene-vinylacetate from Air Products and ChemicalsInc., acrylic-vinyl acetate copolymer emulsions, such as Rhoplex® AR-74from Rohm and Haas Company, Synthemul® 97-726 from Reichhold ChemicalsInc., Resyn® 25-1140, 25-1141, 25-1142, and Resyn-6820 from NationalStarch and Chemical Corporation, vinyl acrylic terpolymer latices, suchas 76 RES 3103 from Union Oil Chemical Division, and Resyn® 251110 fromNational Starch and Chemical Corporation, acrylic emulsion latices, suchas Rhoplex® B-15J, Rhoplex® P-376, Rhoplex® TR-407, Rhoplex® E-940,Rhoplex® TR934, Rhoplex® TR-520, Rhoplex® HA-24, and Rhoplex® NW1825from Rohm and Haas Company, and Hycar® 2600 X 322, Hycar® 2671, Hycar®2679, Hycar®26120, and Hycar® 2600 X347 from B. F. Goodrich ChemicalGroup, styrene-butadiene latices, such as 76 RES 4100 and 76 RES 8100available from Union Oil Chemicals Division, Tylac® resin emulsion68-412, Tylac® resin emulsion 68-067, 68-319, 68-413, 68-500, 68-501,available from Reichhold Chemical Inc., and DL6672A, DL6663A, DL6638A,DL6626A, DL6620A, DL615A, DL617A, DL620A, DL640A, DL650A available fromDow Chemical Company; and rubber latices, such as neoprene availablefrom Serva Biochemicals; polyester latices, such as Eastman AQ 29Davailable from Eastman Chemical Company; vinyl chloride latices, such asGeon® 352 from B. F. Goodrich Chemical Group; ethylene-vinyl chloridecopolymer emulsions, such as Airflex® ethylene-vinyl chloride from AirProducts and Chemicals; polyvinyl acetate homopolymer emulsions, such asVinac® from Air Products and Chemicals; carboxylated vinyl acetateemulsion resins, such as Synthemul® synthetic resin emulsions 40-502,40-503, and 97-664 from Reichhold Chemicals Inc. and Polyco® 2149, 2150,and 2171 from Rohm and Haas Company. Silicone emulsions and binders canalso be considered.

[0079] The co-binder polymer can comprise surface active compounds thatimprove the wettability of the substrate after application of the bindermixture.

[0080] Wettability of a dry substrate that has been treated with aion-sensitive polymer formulation can be a problem in some embodiments,because the hydrophobic portions of the ion-sensitive polymerformulation can become selectively oriented toward the air phase duringdrying, creating a hydrophobic surface that can be difficult to wet whenthe wetting composition is later applied unless surfactants are added tothe wetting composition. Surfactants, or other surface activeingredients, in co-binder polymers can improve the wettability of thedried substrate that has been treated with an ion-sensitive polymerformulation. Surfactants in the co-binder polymer should notsignificantly interfere with the ion-sensitive polymer formulation.Thus, the binder should maintain good integrity and tactile propertiesin the pre-moistened wipes with the surfactant present.

[0081] In one embodiment, an effective co-binder polymer replaces aportion of the ion-sensitive polymer formulation and permits a givenstrength level to be achieved in a pre-moistened wipe with at least oneof lower stiffness, better tactile properties (e.g., lubricity orsmoothness), or reduced cost, relative to an otherwise identicalpre-moistened wipe lacking the co-binder polymer and comprising theion-sensitive polymer formulation at a level sufficient to achieve thegiven tensile strength.

[0082] Other Co-binder Polymers

[0083] The Dry Emulsion Powder (DEP) binders of Wacker Polymer Systems(Burghausen, Germany) such as the VINNEK® system of binders, can beapplied in some embodiments of the present invention. These areredispersible, free flowing binder powders formed from liquid emulsions.Small polymer particles from a dispersion are provided in a protectivematrix of water soluble protective colloids in the form of a powderparticle. The surface of the powder particle is protected against cakingby platelets of mineral crystals. As a result, polymer particles thatonce were in a liquid dispersion are now available in a free flowing,dry powder form that can be redispersed in water or turned into swollen,tacky particles by the addition of moisture. These particles can beapplied in highloft nonwovens by depositing them with the fibers duringthe airlaid process, and then later adding 10% to 30% moisture to causethe particles to swell and adhere to the fibers. This can be called the“chewing gum effect,” meaning that the dry, non-tacky fibers in the webbecome sticky like chewing gum once moistened. Good adhesion to polarsurfaces and other surfaces is obtained. These binders are available asfree flowing particles formed from latex emulsions that have been driedand treated with agents to prevent cohesion in the dry state. They canbe entrained in air and deposited with fibers during the airlaidprocess, or can be applied to a substrate by electrostatic means, bydirect contact, by gravity feed devices, and other means. They can beapplied apart from the binder, either before or after the binder hasbeen dried. Contact with moisture, either as liquid or steam, rehydratesthe latex particles and causes them to swell and to adhere to thefibers. Drying and heating to elevated temperatures (e.g., above 160°C.) causes the binder particles to become crosslinked and waterresistant, but drying at lower temperatures (e.g., at 110° C. or less)can result in film formation and a degree of fiber binding withoutseriously impairing the water dispersibility of the pre-moistened wipes.Thus, it is believed that the commercial product can be used withoutreducing the amount of crosslinker by controlling the curing of theco-binder polymer, such as limiting the time and temperature of dryingto provide a degree of bonding without significant crosslinking.

[0084] As pointed out by Dr. Klaus Kohlhammer in “New Airlaid Binders,”Nonwovens Report International, September 1999, issue 342, pp. 20-22,28-31, dry emulsion binder powders have the advantage that they caneasily be incorporated into a nonwoven or airlaid web during formationof the web, as opposed to applying the material to an existingsubstrate, permitting increased control over placement of the co-binderpolymer. Thus, a nonwoven or airlaid web can be prepared already havingdry emulsion binders therein, followed by moistening when theion-sensitive polymer formulation solution is applied, whereupon the dryemulsion powder becomes tacky and contributes to binding of thesubstrate. Alternatively, the dry emulsion powder can be entrapped inthe substrate by a filtration mechanism after the substrate has beentreated with ion-sensitive binder and dried, whereupon the dry emulsionpowder is rendered tacky upon application of the wetting composition.

[0085] In yet another embodiment, the dry emulsion powder maybedispersed into the ion-sensitive polymer formulation solution either byapplication of the powder as the ion-sensitive polymer formulationsolution is being sprayed onto the web or by adding and dispersing thedry emulsion powder particles into the ion-sensitive polymer formulationsolution, after which the mixture is applied to a web by spraying, byfoam application methods, or by other techniques known in the art.

[0086] Binder Formulations and Fabrics Containing the Same

[0087] The polymer formulations of the present invention may be used asbinders. The binder formulations of the present invention may be appliedto any fibrous substrate. The binders are particularly suitable for usein water-dispersible products. Suitable fibrous substrates include, butare not limited to, nonwoven and woven fabrics. In many embodiments,particularly personal care products, preferred substrates are nonwovenfabrics.

[0088] The binder composition may be applied to the fibrous substrate byany known process of application. Suitable processes for applying thebinder material include, but are not limited to, printing, spraying,electrostatic spraying, coating, flooded nips, metered press rolls,impregnating or by any other technique. The amount of binder compositionmay be metered and distributed uniformly within the fibrous substrate ormay be non-uniformly distributed within the fibrous substrate. Thebinder composition may be distributed throughout the entire fibroussubstrate or it may be distributed within a multiplicity of smallclosely spaced areas. In most embodiments, uniform distribution ofbinder composition is desired.

[0089] For ease of application to the fibrous substrate, the binder maybe dissolved in water, or in a non-aqueous solvent such as methanol,ethanol, acetone, or the like, with water being the preferred solvent.The amount of binder dissolved in the solvent may vary depending on thepolymer used and the fabric application. Desirably, the binder solutioncontains up to about 25 percent by weight of binder composition solids,more desirably, the binder solution contains from about 5 to about 20percent by weight of binder composition solids, more desirably stillfrom about 10 to about 15 percent by weight of binder compositionsolids, and most desirably about 15 percent by weight binder compositionsolids. Plasticizers, perfumes, coloring agents, antifoams,bactericides, preservative, surface active agents, thickening agents,fillers, opacifiers, tackifiers, detackifiers, and the like can beincorporated into the solution of binder components, if so desired.

[0090] Once the binder composition is applied to the substrate, thesubstrate is dried by any conventional means. Once dry, the coherentfibrous substrate exhibits improved tensile strength when compared tothe tensile strength of the untreated wet-laid or dry-laid substrates,and yet has the ability to rapidly “fall apart” or disintegrate whenplaced in soft or hard water having a relatively high divalent and/ormultivalent ionic concentration and agitated. For example, the drytensile strength of the fibrous substrate may be increased by at leastabout 25 percent as compared to the dry tensile strength of theuntreated substrate not containing the binder. More particularly, thedry tensile strength of the fibrous substrate may be increased by atleast about 100 percent as compared to the dry tensile strength of theuntreated substrate not containing the binder. Even more particularly,the dry tensile strength of the fibrous substrate may typically beincreased by at least 500 percent as compared to the dry tensilestrength of the untreated substrate not containing the binder.

[0091] Desirably, however, less than about 20% of the fibers of thefibrous substrate have a length of about 6 to about 10 mm, with theremainder of the fibers having a shorter length. The inclusion of such apercentage of fibers having a length of about 6 to about 10 mm, moredesirably about 7 to about 9 mm, and most desirably about 8 mm, providesunexpected dry and wet tensile strength characteristics. It has beendetermined that where less than about 20% of the fibers, desirably about3 to about 17% and most desirably about 15% of the fibers have a lengthof about 6 to about 10 mm in length that unexpected strength andintegrity characteristics of the fabric or sheet are achieved withoutsignificantly impairing or compromising the dispersibility of theproduct and without promotion of the probability of roping or tangling.Desirably about 3 to about 17%, and more desirably about 5 to about 15%of the fibers have a length of about 6 to about 10 mm. Even moredesirably, about 10 to about 15% of the fibers have a length of about 7to about 9 mm, and most desirably about 10 to about 15% of the fibershave a length of about 8 mm. Although longer fiber lengths will work,and are within the scope of the invention, it is desired that the upperend of the length of fibers used in the present invention be about 15 mmor less, so that tangling and flushing (e.g. getting caught onprotusions in the pipes of the sewer) concerns are minimized. It isfurthermore, desired to keep the fiber length at about 8 mm for maximumeffect with a minimum amount of production throughput concerns.

[0092] As a result of the unexpected fabric strength achieved by theinclusion of the proportion of fibers having the lengths describedabove, it has been determined that the amount of binder may besignificantly reduced, the wetting of the fibers is increased and theprocessing or line speeds are able to be increased. Processing orconverting speeds maybe increased as it is believed that fibers providesufficient strength for the processing speeds and the lower amounts ofbinder allow the fibers to wet (i.e. be treated) easier. Whereas, thehigher amounts of binder typically inhibit sheet penetration and thusrequire longer exposure to the treatment in order to achieve the sameend result.

[0093] Desirably one embodiment of the present invention may containsabout 5 to about 25% by weight of binder, more desirably about 10 toabout 20% by weight, and about 75 to about 95% by weight fiber, moredesirably about 80 to about 90% by weight fiber. The reduction of binderor glue below about 25%, and desirably about 20%, by weight allows thefibers of the fabric to wet easier as the binder tends not to create acomplete film across the fabric. Due in part to the strengthcharacteristics and in part to the increase in fiber wettability,process or line speeds of the fabric manufacturing may be increased

[0094] A desirable feature of the present invention is that theimprovement in tensile strength is effected where the amount of bindercomposition present, “add-on”, in the resultant fibrous substraterepresents only a small portion by weight of the entire substrate. Theamount of “add-on” can vary for a particular application; however, theoptimum amount of “add-on” results in a fibrous substrate which hasintegrity while in use and also quickly disperses when agitated inwater. For example, the binder components typically are from about 5 toabout 65 percent, by weight, of the total weight of the substrate. Moreparticularly, the binder components may be from about 5% to about 35% ofthe total weight of the substrate, but are desirably less than about 25%by weight, more desirably from about 5 to less than about 20% by weight,and even more desirably, the binder components may be from about 10 toabout 15% by weight of the total weight of the substrate.

[0095] The nonwoven fabrics of the present invention have good in-usetensile strength, as well as, ion triggerability. Desirably, thenonwoven fabrics of the present invention are abrasion resistant andretain significant tensile strength in aqueous solutions containinggreater than about 0.3 weight percent NaCl, or a mixture of monovalentions, for those formulations using the acrylic acid terpolymer, andgreater than about 0.3 weight percent NaCl, or a mixture of monovalentions, for those formulations using the sulfonate anion modified acrylicacid terpolymer. Yet, the nonwoven fabrics are dispersible in very softto moderately hard to hard water. Because of this latter property,nonwoven fabrics of the present invention are well suited for disposableproducts, such as sanitary napkins, diapers, adult incontinenceproducts, and dry and premoistened wipes (wet wipes), which can bethrown in a flush toilet after use in any part of the world.

[0096] The fibers forming the fabrics above can be made from a varietyof materials including natural fibers, synthetic fibers, andcombinations thereof. The choice of fibers depends upon, for example,the intended end use of the finished fabric and fiber cost. Forinstance, suitable fibrous substrates may include, but are not limitedto, natural fibers such as cotton, linen, jute, hemp, wool, wood pulp,etc. Similarly, regenerated cellulosic fibers, such as viscose rayon andcuprammonium rayon and lyocell rayon, modified cellulosic fibers, suchas cellulose acetate, or synthetic fibers, such as those derived frompolypropylenes, polyethylenes, polyolefins, polyesters, polyamides,polyacrylics, etc., alone or in combination with one another, maylikewise be used. Blends of one or more of the above fibers may also beused, if so desired. Among wood pulp fibers, any known papermakingfibers may be used, including softwood and hardwood fibers. Fibers, forexample, may be chemically pulped or mechanically pulped, bleached orunbleached, virgin or recycled, high yield or low yield, and the like.Mercerized, chemically stiffened or crosslinked fibers may also be used.

[0097] In one embodiment of the present invention it is desirable for atleast about 80% of the fiber fraction of the fibrous substrate tocomprise a pulp or cellulosic fiber and less than about 20% of thefibers of the fibrous substrate to comprise synthetic fibers. Even moredesirably, about 85 to about 95% of the fiber fraction is pulp orcellulose, and about 5 to about 15% is synthetic fibers.

[0098] Synthetic cellulose fiber types include rayon in all itsvarieties and other fibers derived from viscose or chemically modifiedcellulose, including regenerated cellulose and solvent-spun cellulose,such as lyocell. A desired synthetic cellulose fiber is TENCEL®,available from Acordis Cellulosic Fibers, located in the United Kingdom.Chemically treated natural cellulosic fibers, such as mercerized pulps,chemically stiffened or crosslinked fibers, or sulfonated fibers, mayalso be used. Recycled fibers, as well as virgin fibers, can be used.Cellulose produced by microbes and other cellulosic derivatives can beused. The fibers, particularly synthetic fibers, can also be crimped.

[0099] To the extent described herein, the fiber length is important inproducing the fabrics of the present invention. In some embodiments,such as flushable products, fiber length is of more importance. Theminimum length of the fibers depends on the method selected for formingthe fibrous substrate. For example, where the fibrous substrate isformed by carding, the length of the fiber should usually be at leastabout 42 mm in order to insure uniformity. Where the fibrous substrateis formed by air-laid or wet-laid processes, the fiber length maydesirably be about 0.2 to about 12 mm. Although fibers having a lengthof greater than about 50 mm are within the scope of the presentinvention, it has been determined that when a substantial quantity offibers having a length greater than about 15 mm is placed in a flushablefabric, though the fibers will disperse and separate in water, theirlength tends to form “ropes” of fibers, which are undesirable whenflushing in home toilets. Therefore, for these products, it is desiredthat the fiber length be about 15 mm or less so that the fibers will nothave a tendency to “rope” when they are flushed through a toilet.Furthermore, fibers having a length of greater than about 15 mm inlength also have an increased chance of getting caught on something inor extending into sewer system and/or pipes connected thereto, whetheror not the fibers have experienced roping. Thus while fibers of variouslengths are applicable in the present invention, desirably fibers are ofa length less than about 15 mm so that the fibers disperse easily fromone another when in contact with water.

[0100] As above, it has been determined that when a certain percent offibers having a length of about 6 to about 10 mm are incorporated intothe fabric or article that certain unexpected strength characteristicsare exhibited. Specifically, where the fibrous substrate of theabsorbent article comprises less than about 20% fiber fraction having alength of about 6 to about 10 mm, desirably about 3 to about 17%, andeven more desirably about 5 to about 15%. Most desirably, about 15% ofthe fibers of the fibrous substrate will be about 8 mm in length andwill be synthetic. The remaining fibers are desirably pulp and celluloseand are desirably shorter in length. As illustrated shown in tablesbelow, and discussed in more detail in connection with the examples, afibrous substrate comprising less than about 20% fiber fraction having alength of about 6 to about 10 mm in length, with the remaining fibersgenerally being shorter in length, an increase in Dry Tensile strengthis experienced versus substrates having generally shorter fibers. Aneven greater unexpected strength is exhibited by fabrics or compositionsof the present invention which include the above mentioned percentage ofsynthetic fibers which are about 8 mm in length. Without wishing to bebound by theory, it is believed by the inventors that this unexpectedstrength characteristic results yet still allows for the product to bedispersible as desired because of the presence of a sufficient number offibers of sufficient length so as far as to provide for the engagementand/or overlapping of these fibers (which may include interweaving orentangling) to an extent and in such a manner that the fibers are notreadily able to be pulled apart, yet the fibers are not of such lengthas to be so engaged or overlapping as to not be readily dispersed asdiscussed in more detail herein.

[0101] The fabrics of the present invention may be formed from a singlelayer or multiple layers. In the case of multiple layers, the layers aregenerally positioned in a juxtaposed or surface-to-surface relationshipand all or a portion of the layers may be bound to adjacent layers.Nonwoven webs of the present invention may also be formed from aplurality of separate nonwoven webs wherein the separate nonwoven websmay be formed from single or multiple layers. In those instances wherethe nonwoven web includes multiple layers, the entire thickness of thenonwoven web may be subjected to a binder application or each individuallayer may be separately subjected to a binder application and thencombined with other layers in a juxtaposed relationship to form thefinished nonwoven web. It is believed that the present inventionprovides for the use of thicker monolayer and/or multilayer, (as thuspotentially thicker) products yet still provide the desireddispersibility, whereas other products may be limited in the thicknessor number of layers in order to achieve the desired dispersibility.

[0102] In one embodiment, the fabric of the present invention may beincorporated into cleansing and body fluid absorbent products, such assanitary napkins, diapers, adult incontinence products, surgicaldressings, tissues, wet wipes, and the like. These products may includean absorbent core, comprising one or more layers of an absorbent fibrousmaterial. The core may also comprise one or more layers of afluid-pervious element, such as fibrous tissue, gauze, plastic netting,etc. These are generally useful as wrapping materials to hold thecomponents of the core together. Additionally, the core may comprise afluid-impervious element or barrier means to preclude the passage offluid through the core and on the outer surfaces of the product.Desirably, the barrier means is also water-dispersible. A film of apolymer having substantially the same composition as the aforesaidwater-dispersible binder is particularly well-suited for this purpose.In accordance with the present invention, the polymer compositions areuseful for forming each of the above-mentioned product componentsincluding but not limited to the layers of absorbent core, thefluid-pervious element, the wrapping materials, and the fluid-imperviouselement or barrier means.

[0103] The binder formulations of the present invention are alsoparticularly useful for binding fibers of air-laid nonwoven fabrics.These air-laid materials are useful for body-side liners, fluiddistribution materials, fluid intake materials, such as a surgematerial, absorbent wrap sheet and cover stock for variouswater-dispersible personal care products. Air-laid materials areparticularly useful for use as a pre-moistened wipe (wet wipe). Thebasis weights for air-laid non-woven fabrics may range from about 20 toabout 200 grams per square meter (“gsm”) with staple fibers having adenier of about 0.5-10 and a length of about 6-15 millimeters. Surge, orintake, materials need better resiliency and higher loft so staplefibers having about 6 denier or greater are used to make these products.A desirable final density for the surge, or intake, materials is betweenabout 0.025 grams per cubic centimeter (“g/cc”) to about 0.10 g/cc.Fluid distribution materials may have a higher density, in the desiredrange of about 0.10 to about 0.20 g/cc using fibers of lower denier,most desirable fibers have a denier of less than about 1.5. Wipesgenerally can have a fiber density of about 0.025 g/cc to about 0.2 g/ccand a basis weight of about 20 gsm to about 150 gsm; desirably fromabout 30 to about 90 gsm, and most desirably from about 60 gsm to about65 gsm.

[0104] The nonwoven fabrics of the present invention may also beincorporated into such body fluid absorbing products as sanitarynapkins, diapers, surgical dressings, tissues and the like. In oneembodiment, the binder is such that it will not dissolve when contactedby body fluids since the concentration of monovalent ions in the bodyfluids is above the level needed for dissolution; i.e., greater thanabout 0.3% by weight and/or greater than about 1% by weight. Thenonwoven fabric retains its structure, softness and exhibits a toughnesssatisfactory for practical use. However, when brought into contact withwater having a concentration of divalent and/or multivalent ions, suchas Ca²⁺ and Mg²⁺ ions, of up to about 200 ppm, the binder, such as onecomprising a sulfonate anion modified acrylic acid terpolymer,disperses. The nonwoven fabric structure is then easily broken anddispersed in the water. Desirably, the composition of the presentinvention is dispersible in water containing from about 15 ppm to about50 ppm of one or more divalent and/or multivalent ions, more desirablybeing dispersible in water containing from about 15 ppm to about 100 ppmof one or more divalent and/or multivalent ions, more desirably beingdispersible in water containing from about 15 ppm to about 150 ppm ofone or more divalent and/or multivalent ions, and most desirably beingdispersible in water containing from about 15 ppm to about 200 ppm ofone or more divalent and/or multivalent ions. While most of the waterthe material of the present invention is likely to encounter has aconcentration of divalent and/or multivalent ions between about 15 ppmand about 200 ppm, it is also desirable that when brought into contactwith water having a concentration of divalent and/or multivalent ionsless than about 15 ppm, and more specifically less than about 10 ppm,the binder of the of the present invention comprising the acrylic acidterpolymer disperses as well. Similarly, the nonwoven fabric structureis then easily broken and dispersed in the water.

[0105] In one or more embodiments of the present invention it isdesirable for the water dispersible fibrous fabric to be capable ofdispersion in water after no more than about 60 minutes, more desirablyafter no more than about 20 minutes, and more desirably to disperse inwater after no more than about 10 minutes. Furthermore, it alsodesirable that wherein after up to about 60 minutes, more desirably upto about 20 minutes, of exposure to water that the fibrous material ofthe present invention break up into multiple pieces each having anaverage size of less than about 50% relative to its pre-dispersed size,more desirably into multiple pieces each having an average size of lessthan about 40% relative to its pre-dispersed size, and even moredesirably into multiple pieces each having an average size of less thanabout 30% relative to its pre-dispersed size.

[0106] In one embodiment of the present invention, the in-use tensilestrength of a nonwoven fabric is enhanced by forming the nonwoven fabricwith a binder material comprising an ion-sensitive polymer formulationof the present invention and subsequently applying one or moremonovalent and/or divalent and/or multivalent salts to the nonwovenfabric. The salt may be applied to the nonwoven fabric by any methodknown to those of ordinary skill in the art including, but not limitedto, applying a solid powder onto the fabric and spraying a salt solutiononto the fabric. The amount of salt may vary depending on a particularapplication. However, the amount of salt applied to the fabric istypically from about 0.1 weight percent to about 10 weight percent saltsolids based on the total weight of the fabric. The salt-containingfabrics of the present invention may be used in a variety of fabricapplications including, but not limited to, feminine pads, surgicaldressings, and diapers.

[0107] Those skilled in the art will readily understand that the binderformulations and fibrous substrates of the present invention may beadvantageously employed in the preparation of a wide variety ofproducts, including but not limited to, absorbent personal care productsdesigned to be contacted with body fluids. Such products may onlycomprise a single layer of the fibrous substrate, or may comprise acombination of elements, as described above. Although the binderformulations and fibrous substrates of the present invention areparticularly suited for personal care products, the binder formulationsand fibrous substrates may be advantageously employed in a wide varietyof consumer products. Exemplary personal care products include, but arenot limited to, a wipe, diaper, training pant, swimwear, absorbentunderpant, adult incontinence product, feminine hygiene product,absorbent pad, wound dressing and bandage.

[0108] The combination of the acrylic acid terpolymer or the sulfonateanion modified acrylic acid terpolymer and the non-crosslinkingpoly(ethylene-vinyl acetate) of the present invention produces improvedresults over the use of the terpolymer alone. For example, when theion-sensitive polymer formulation of the present invention is used for abinder composition for wet wipes, the wet wipes have improvedwettability on first insult without losing dispersibility which allowsthe wipe basesheet to wet out easily with the wet wipe solution atcommercial speeds. The ion-sensitive polymer formulation of the presentinvention also can reduce the stiffness of the dry basesheet, improvethe runnability of the dry and otherwise brittle sheet during furtherconversion of the product, reduce the stickiness of the wipes and/orimprove the sprayability of the ion-sensitive binder, thereby improvingbinder distribution and penetration in the basesheet.

[0109] Unlike other binder systems known in the art, the ion-sensitivepolymer formulations of the present invention can be activated asbinders without the need for elevated temperature. While drying or waterremoval is useful in achieving a good distribution of the binder in afibrous web, elevated temperature, per se, is not essential because thebinder does not require crosslinking or other chemical reactions withhigh activation energy to serve as a binder. Rather, the interactionwith a soluble activating compound, typically a salt, is sufficient tocause the binder to become active (insoluble) or “salted out.” Thus, adrying step can be avoided, if desired, or replaced with low-temperaturewater removal operations such as room-temperature drying or freezedrying. Elevated temperature is generally helpful for drying, but thedrying can be done at temperatures below what is normally needed todrive crosslinking reactions. Thus, the peak temperature to which thesubstrate is exposed or to which the substrate is brought can be belowany of the following: about 220° C., about 200° C., about 180° C., about160° C., about 140° C., about 120° C., about 110° C., about 105° C.,about 100° C., about 90° C., about 75° C., and about 60° C. Of course,higher temperatures can be used, but are not necessary in mostembodiments. While co-binder polymer systems, such as commercial latexemulsions, may also comprise crosslinkers suited for reaction attemperatures of about 160° C. or higher, maintaining a lower peaktemperature can be beneficial in preventing development of excessivestrength in the co-binder polymer that might otherwise hinder the waterdispersibility of the pre-moistened wipe.

[0110] Wet Wipe Wetting Composition and Wet Wipes Containing the Same

[0111] Another embodiment of the present invention is the production ofpre-moistened wipes, or wet wipes, from the above-describedion-sensitive binder compositions and fibrous materials. Exemplaryembodiments of wet wipes of the present invention are illustrated inFIGS. 1 and 2. For wipes, the fibrous material may be in the form of awoven or nonwoven fabric; however, nonwoven fabrics are more desirable.The nonwoven fabric is, desirably, formed from relatively short fibers,such as wood pulp fibers. The minimum length of the fibers depends onthe method selected for forming the nonwoven fabric. Where the nonwovenfabric is formed by a wet or dry method, the fiber length is desirablyfrom about 0.1 millimeters to about 15 millimeters. Desirably, thenonwoven fabric of the present invention has a relatively low wetcohesive strength when it is not bonded together by an adhesive orbinder material. When such nonwoven fabrics are bonded together by abinder composition, which loses its bonding strength in tap water and insewer water, the fabric will break up readily by the agitation providedby flushing and moving through the sewer pipes.

[0112] The finished wipes may be individually packaged, desirably in afolded condition, in a moisture proof envelope or packaged in containersholding any desired number of sheets in a watertight package with awetting composition applied to the wipe. The finished wipes may also bepackaged as a roll of separable sheets (as illustrated in FIG. 3) in amoisture-proof container holding any desired number of sheets on theroll with a wetting composition applied to the wipes. The roll can becoreless and either hollow or solid. Coreless rolls, including rollswith a hollow center or without a solid center, can be produced withknown coreless roll winders, including those of SRP Industry, Inc. (SanJose, Calif.); Shimizu Manufacturing (Japan), and the devices disclosedin U.S. Pat. No. 4,667,890, issued May 26, 1987 to Gietman. Solid-woundcoreless rolls can offer more product for a given volume and can beadapted for a wide variety of dispensers.

[0113] Relative to the weight of the dry fabric, the wipe may desirablycontain from about 10 percent to about 400 percent of the wettingcomposition, more desirably from about 100 percent to about 300 percentof the wetting composition, and even more desirably from about 180percent to about 240 percent of the wetting composition. The wipemaintains its desired characteristics over the time periods involved inwarehousing, transportation, retail display and storage by the consumer.Accordingly, shelf life may range from two months to two years.

[0114] Various forms of impermeable envelopes and storage means forcontaining wet-packaged materials such as wipes and towelettes and thelike are well known in the art. Any of these may be employed inpackaging the pre-moistened wipes of the present invention.

[0115] Desirably, the pre-moistened wipes of the present invention arewetted with an aqueous wetting composition, which has one or more of thefollowing properties:

[0116] (1) is compatible with the above-described ion-sensitive bindercompositions of the present invention;

[0117] (2) enables the pre-moistened wipe to maintain its wet strengthduring converting, storage and usage (including dispensing), as well as,dispersibility in a toilet bowl;

[0118] (3) does not cause skin irritation;

[0119] (4) reduces tackiness of the wipe, and provides unique tactileproperties, such as skin glide and a “lotion-like feel”; and

[0120] (5) acts as a vehicle to deliver “moist cleansing” and other skinhealth benefits.

[0121] The wetting composition should not act as a solvent for thebinder and generally does not contain solvents other than water, anddesirably does not contain organic solvents, though a small quantity(generally less than about 1%) of a fragrance solubilizer such aspolysorbate 20 may be present, depending on the fragrance and the saltconcentration of the wetting composition. Desirably, the wettingcomposition contains less than about 10 weight percent of organicsolvents, such as propylene glycol or other glycols, polyhydroxyalcohols, and the like, based on the total weight of the wettingcomposition. More desirably, the wetting composition contains less thanabout 4 weight percent of organic solvents. Even more desirably, thewetting composition contains less than about 1 weight percent of organicsolvents. The wetting composition can be substantially free of organicsolvents.

[0122] One aspect of the present invention is a wetting composition,which contains an activating compound that maintains the strength of awater-dispersible binder until the activating compound is diluted withwater, whereupon the strength of the water-dispersible binder begins todecay. The water-dispersible binder may be any of the ion-sensitivebinder compositions of the present invention or any other suitableion-sensitive binder composition. The activating compound in the wettingcomposition can be a salt, such as sodium chloride, or any othercompound, which provides in-use and storage strength to thewater-dispersible binder composition, and can be diluted in water topermit dispersion of the substrate as the binder polymer triggers to aweaker state. Desirably, the wetting composition contains less thanabout 10 weight percent of an activating compound based on the totalweight of the wetting composition. Desirably, the wetting compositionmay contain from about 0.3 weight percent to about 5 weight percent ofan activating compound. Even more desirably, the wetting composition maycontain from about 2 weight percent to about 4 weight percent of anactivating compound.

[0123] The wetting composition of the present invention may furthercomprise a variety of additives compatible with the activating compoundand the water-dispersible binder, such that the strength anddispersibility functions of the wipe are not jeopardized. Suitableadditives in the wetting composition include, but are not limited to,the following additives: skin-care additives; odor control agents;detackifying agents to reduce the tackiness of the binder; particulates;antimicrobial agents; preservatives; wetting agents and cleaning agentssuch as detergents, surfactants, and some silicones; emollients; surfacefeel modifiers for improved tactile sensation (e.g., lubricity) on theskin; fragrance; fragrance solubilizers; opacifiers; fluorescentwhitening agents; UV absorbers; pharmaceuticals; and pH control agents,such as malic acid or potassium hydroxide.

[0124] Skin-Care Additives

[0125] Fecal enzymes, particularly trypsin, chymotrypsin and elastase,are proteolytic enzymes produced in the gastrointestinal tract to digestfood. In infants, for example, the feces tend to be watery and contain,among other materials, bacteria, and some amounts of undegradeddigestive enzymes. These enzymes, if they remain in contact with theskin for any appreciable period of time, have been found to cause anirritation that is uncomfortable in itself and can predispose the skinto infection by microorganisms. As a countermeasure, skin-care additivesinclude, but are not limited to, the enzyme inhibitors and sequestrantsset forth hereafter. The wetting composition may contain less than about5 weight percent of skin-care additives based on the total weight of thewetting composition. More desirably, the wetting composition may containfrom about 0.01 weight percent to about 2 weight percent of skin-careadditives. Even more desirably, the wetting composition may contain fromabout 0.01 weight percent to about 0.05 weight percent of skin-careadditives.

[0126] A variety of skin-care additives may be added to the wettingcomposition and the pre-moistened wipes of the present invention orincluded therein. In one embodiment of the present invention, skin-careadditives in the form of particles are added to serve as fecal enzymeinhibitors, offering potential benefits in the reduction of diaper rashand skin damage caused by fecal enzymes. U.S. Pat. No. 6,051,749, issuedApr. 18, 2000 to Schulz et al., the entirety of which is hereinincorporated by reference, discloses organophilic clays in a woven ornonwoven web, said to be useful for inhibiting fecal enzymes. Suchmaterials may be used in the present invention, including reactionproducts of a long chain organic quaternary ammonium compound with oneor more of the following clays: montmorillonite, bentonite, beidellite,hectorite, saponite, and stevensite.

[0127] Other known enzyme inhibitors and sequestrants may be used asskin-care additives in the wetting composition of the present invention,including those that inhibit trypsin and other digestive or fecalenzymes, and inhibitors for urease. For example, enzyme inhibitors andanti-microbial agents may be used to prevent the formation of odors inbody fluids. For example, urease inhibitors, which are also said to playa role in odor absorption, are disclosed by T. Trinh in World PatentApplication No. 98/26808, “Absorbent Articles with Odor Control System,”published Jun. 25, 1998, the entirety of which is herein incorporated byreference. Such inhibitors may be incorporated into the wettingcomposition and the pre-moistened wipes of the present invention andinclude transition metal ions and their soluble salts, such as silver,copper, zinc, ferric, and aluminum salts. The anion may also provideurease inhibition, such as borate, phytate, etc. Compounds of potentialvalue include, but are not limited to, silver chlorate, silver nitrate,mercury acetate, mercury chloride, mercury nitrate, copper metaborate,copper bromate, copper bromide, copper chloride, copper dichromate,copper nitrate, copper salicylate, copper sulfate, zinc acetate, zincborate, zinc phytate, zinc bromate, zinc bromide, zinc chlorate, zincchloride, zinc sulfate, cadmium acetate, cadmium borate, cadmiumbromide, cadmium chlorate, cadmium chloride, cadmium formate, cadmiumiodate, cadmium iodide, cadmium permanganate, cadmium nitrate, cadmiumsulfate, and gold chloride.

[0128] Other salts that have been disclosed as having urease inhibitionproperties include ferric and aluminum salts, especially the nitrates,and bismuth salts. Other urease inhibitors are disclosed by Trinh,including hydroxamic acid and its derivatives; thiourea; hydroxylamine;salts of phytic acid; extracts of plants of various species, includingvarious tannins, e.g. carob tannin, and their derivatives such aschlorogenic acid derivatives; naturally occurring acids such as ascorbicacid, citric acid, and their salts; phenyl phosphoro diamidate/diaminophosphoric acid phenyl ester; metal aryl phosphoramidate complexes,including substituted phosphorodiamidate compounds; phosphoramidateswithout substitution on the nitrogen; boric acid and/or its salts,including especially, borax, and/or organic boron acid compounds; thecompounds disclosed in European Patent Application 408,199 (publishedJun. 15, 1990); sodium, copper, manganese, and/or zinc dithiocarbamate;quinones; phenols; thiurams; substituted rhodanine acetic acids;alkylated benzoquinones; formamidine disulphide; 1:3-diketones maleicanhydride; succinamide; phthalic anhydride; pehenic acid;N,N-dihalo-2-imidazolidinones; N-halo2-oxazolidinones; thio- and/oracyl-phosphoryltnamide and/or substituted derivatives thereof,thiopyridine-N-oxides, thiopyridines, and thiopyrimidines; oxidizedsulfur derivatives of diarninophosphinyl compounds;cyclotriphosphazatriene derivatives; ortho-diaminophosphinyl derivativesof oximes; bromo-nitro compounds; S-aryl and/or alkyldiamidophosphorothiolates; diaminophosphinyl derivatives; mono- and/orpolyphosphorodiamide; 5-substituted-benzoxathiol-2-ones;N(diaminophosphinyl)arylcarboxamides; alkoxy-1,2-benzothaizin compounds;etc.

[0129] Many other skin-care additives may be incorporated into thewetting composition and pre-moistened wipes of the present invention,including, but not limited to, sun blocking agents and UV absorbers,acne treatments, pharmaceuticals, baking soda (including encapsulatedforms thereof), vitamins and their derivatives such as Vitamins A or E,botanicals such as witch hazel extract and aloe vera, allantoin,emollients, disinfectants, hydroxy acids for wrinkle control oranti-aging effects, sunscreens, tanning promoters, skin lighteners,deodorants and anti-perspirants, ceramides for skin benefits and otheruses, astringents, moisturizers, nail polish removers, insectrepellants, antioxidants, antiseptics, anti-inflammatory agents and thelike, provided that the additives are compatible with an ion-sensitivebinder composition associated therewith, and especially theion-sensitive binder compositions of the present invention (i.e., theydo not cause a substantial loss of strength in the wet state of thepre-moistened wipes, prior to dilution in water, while permittingdispersibility in water).

[0130] Useful materials for skin care and other benefits are listed inMcCutcheon's 1999, Vol. 2: Functional Materials, MC Publishing Company,Glen Rock, N.J. Many useful botanicals for skin care are provided byActive Organics, Lewisville, Tex.

[0131] Odor Control Additives

[0132] Suitable odor control additives for use in the wettingcomposition and pre-moistened wipes of the present invention include,but are not limited to, zinc salts; talc powder; encapsulated perfumes(including microcapsules, macrocapsules, and perfume encapsulated inliposomes, vessicles, or microemulsions); chelants, such asethylenediamine tetra-acetic acid; zeolites; activated silica, activatedcarbon granules or fibers; activated silica particulates; polycarboxylicacids, such as citric acid; cyclodextrins and cyclodextrin derivatives;chitosan or chitin and derivatives thereof; oxidizing agents;antimicrobial agents, including silver-loaded zeolites (e.g., those ofBF Technologies, located in Beverly, Mass., sold under the trademarkHEALTHSHIELD™); triclosan; kieselguhr; and mixtures thereof. In additionto controlling odor from the body or body wastes, odor controlstrategies can also be employed to mask or control any odor of thetreated substrate. Desirably, the wetting composition contains less thanabout 5 weight percent of odor control additives based on the totalweight of the wetting composition. More desirably, the wettingcomposition contains from about 0.01 weight percent to about 2 weightpercent of odor control additives. Even more desirably, the wettingcomposition contains from about 0.03 weight percent to about 1 weightpercent of odor control additives.

[0133] In one embodiment of the present invention, the wettingcomposition and/or pre-moistened wipes comprise derivatizedcyclodextrins, such as hydroxypropyl beta-cyclodextrin in solution,which remain on the skin after wiping and provide an odor-absorbinglayer. In other embodiments, the odor source maybe removed orneutralized by application of an odor-control additive, exemplified bythe action of a chelant that binds metal groups necessary for thefunction of many proteases and other enzymes that commonly produce anodor. Chelating the metal group interferes with the enzyme's action anddecreases the risk of malodor in the product.

[0134] Principles for the application of chitosan or chitin derivativesto nonwoven webs and cellulosic fibers are described by S. Lee et al. in“Antimicrobial and Blood Repellent Finishes for Cotton and NonwovenFabrics Based on Chitosan and Fluoropolymers,” Textile Research Journal,69(2); 104-112, February 1999.

[0135] Detackifying Agents

[0136] While elevated salt concentrations may reduce the tack of theion-sensitive binder, other means of tack reduction are often desirable.Thus, detackifying agents may be used in the wetting composition toreduce the tackiness, if any, of the ion-sensitive binder. Suitabledetackifiers include any substance known in the art to reduce tackbetween two adjacent fibrous sheets treated with an adhesive-likepolymer or any substance capable of reducing the tacky feel of anadhesive-like polymer on the skin. Detackifiers may be applied as solidparticles in dry form, as a suspension or as a slurry of particles.Deposition may be by spray, coating, electrostatic deposition,impingement, filtration (i.e., a pressure differential drives aparticle-laden gas phase through the substrate, depositing particles bya filtration mechanism), and the like, and may be applied uniformly onone or more surfaces of the substrate or may be applied in a pattern(e.g., repeating or random patterns) over a portion of the surface orsurfaces of the substrate. The detackifier may be present throughout thethickness of the substrate, but may be concentrated at one or bothsurfaces, and may be substantially only present on one or both surfacesof the substrate.

[0137] Specific detackifiers include, but are not limited to, powders,such as talc powder, calcium carbonate, mica; starches, such as cornstarch; lycopodium powder; mineral fillers, such as titanium dioxide;silica powder; alumina; metal oxides in general; baking powder;kieselguhr; and the like. Polymers and other additives having lowsurface energy may also be used, including a wide variety of fluorinatedpolymers, silicone additives, polyolefins and thermoplastics, debondingagents known in the paper industry (including compounds having alkylside chains such as those having 16 or more carbons), waxes and thelike. Compounds used as release agents for molds and candle making mayalso be considered, as well as, dry lubricants and fluorinated releaseagents.

[0138] In one embodiment, the detackifier comprisespolytetrafluorethylene (PTFE), such as PTFE telomer (KRYTOX® DF)compound, used in the PTFE release agent dry lubricant MS-122DF,marketed by Miller-Stephenson (Danbury, Conn.) as a spray product. Forexample, PTFE particles may be applied by spray to one side of thesubstrate prior to winding of the pre-moistened wipes. In oneembodiment, a detackifying agent maybe applied to only one surface ofthe substrate prior to winding into a roll.

[0139] The wetting composition desirably contains less than about 25weight percent of detackifying agents based on the total weight of thewetting composition. More desirably, the wetting composition containsfrom about 0.01 weight percent to about 10 weight percent ofdetackifying agents, more desirably about 5% or less. Even moredesirably, the wetting composition contains from about 0.05 weightpercent to about 2 weight percent of detackifying agents.

[0140] In addition to acting as a detackifying agent, starch compoundsmay also improve the strength properties of the pre-moistened wipes. Forexample, it has been found that ungelled starch particles, such ashydrophilic tapioca starch, when present at a level of about 1% orhigher by weight relative to the weight of the wetting composition, canpermit the pre-moistened wipe to maintain the same strength at a lowersalt concentration than is possible without the presence of starch.Thus, for example, a given strength can be achieved with 2% salt in thewetting composition in the presence of salt compared to a level of 4%salt being needed without starch. Starch may be applied by adding thestarch to a suspension of laponite to improve the dispersion of thestarch within the wetting composition.

[0141] Microparticulates

[0142] The wetting composition of the present invention may be furthermodified by the addition of solid particulates or microparticulates.Suitable particulates include, but are not limited to, mica, silica,alumina, calcium carbonate, kaolin, talc, and zeolites. The particulatesmay be treated with stearic acid or other additives to enhance theattraction or bridging of the particulates to the binder system, ifdesired. Also, two-component microparticulate systems, commonly used asretention aids in the papermaking industry, may also be used. Suchtwo-component microparticulate systems generally comprise a colloidalparticle phase, such as silica particles, and a water-soluble cationicpolymer for bridging the particles to the fibers of the web to beformed. The presence of particulates in the wetting composition canserve one or more useful functions, such as (1) increasing the opacityof the pre-moistened wipes; (2) modifying the rheology or reducing thetackiness of the pre-moistened wipe; (3) improving the tactileproperties of the wipe; or (4) delivering desired agents to the skin viaa particulate carrier, such as a porous carrier or a microcapsule.Desirably, the wetting composition contains less than about 25 weightpercent of particulate based on the total weight of the wettingcomposition. More desirably, the wetting composition may contain fromabout 0.05 weight percent to about 10 weight percent ofmicroparticulate. Even more desirably, the wetting composition maycontain from about 0.1 weight percent to about 5 weight percent ofmicroparticulate.

[0143] Microcapsules and Other Delivery Vehicles

[0144] Microcapsules and other delivery vehicles may also be used in thewetting composition of the present invention to provide skin-careagents; medications; comfort promoting agents, such as eucalyptus;perfumes; skin care agents; odor control additives; vitamins; powders;and other additives to the skin of the user. Specifically, the wettingcomposition may contain up to about 25 weight percent of microcapsulesor other delivery vehicles based on the total weight of the wettingcomposition. More desirably, the wetting composition may contain fromabout 0.05 weight percent to about 10 weight percent of microcapsules orother delivery vehicles. Even more desirably, the wetting compositionmay contain from about 0.2 weight percent to about 5 weight percent ofmicrocapsules or other delivery vehicles.

[0145] Microcapsules and other delivery vehicles are well known in theart. For example, POLY-PORE® E200 (Chemdal Corp., Arlington Heights,Ill.), is a delivery agent comprising soft, hollow spheres that cancontain an additive at over 10 times the weight of the delivery vehicle.Known additives reported to have been used with POLY-PORE® E200 include,but are not limited to, benzoyl peroxide, salicylic acid, retinol,retinyl palmitate, octyl methoxycinnamate, tocopherol, siliconecompounds (DC 435), and mineral oil. Another useful delivery vehicle isa sponge-like material marketed as POLY-PORE® L200, which is reported tohave been used with silicone (DC 435) and mineral oil. Other knowndelivery systems include cyclodextrins and their derivatives, liposomes,polymeric sponges, and spray-dried starch.

[0146] Additives present in microcapsules are isolated from theenvironment and the other agents in the wetting composition until thewipe is applied to the skin, whereupon the microcapsules break anddeliver their load to the skin or other surfaces.

[0147] Preservatives and Anti-Microbial Agents

[0148] The wetting composition of the present invention may also containpreservatives and/or anti-microbial agents. Several preservatives and/oranti-microbial agents, such as Mackstat H-66 (available from McIntyreGroup, Chicago, Ill., have been found to give excellent results inpreventing bacteria and mold growth. Other suitable preservatives andanti-microbial agents include, but are not limited to DMDM hydantoin(e.g., Glydant Plus™, Lonza, Inc., Fair Lawn, N.J.), iodopropynylbutylcarbamate, Kathon (Rohm and Hass, Philadelphia, Pa.),methylparaben, propylparaben, 2-bromo-2-nitropropane-1,3-diol, benzoicacid, and the like. Desirably, the wetting composition contains lessthan about 2 weight percent on an active basis of preservatives and/oranti-microbial agents based on the total weight of the wettingcomposition. More desirably, the wetting composition contains from about0.01 weight percent to about 1 weight percent of preservatives and/oranti-microbial agents. Even more desirably, the wetting compositioncontains from about 0.01 weight percent to about 0.5 weight percent ofpreservatives and/or anti-microbial agents.

[0149] Wetting Agents and Cleaning Agents

[0150] A variety of wetting agents and/or cleaning agents may be used inthe wetting composition of the present invention. Suitable wettingagents and/or cleaning agents include, but are not limited to,detergents and nonionic, amphoteric, and anionic surfactants, especiallyamino acid-based surfactants. Amino acid-based surfactant systems, suchas those derived from amino acids L-glutamic acid and other naturalfatty acids, offer pH compatibility to human skin and good cleansingpower, while being relatively safe and providing improved tactile andmoisturization properties compared to other anionic surfactants. Onefunction of the surfactant is to improve wetting of the dry substratewith the wetting composition. Another function of the surfactant can beto disperse bathroom soils when the pre-moistened wipe contacts a soiledarea and to enhance their absorption into the substrate. The surfactantcan further assist in make-up removal, general personal cleansing, hardsurface cleansing, odor control, and the like.

[0151] One commercial example of an amino-acid based surfactant isacylglutamate, marketed under the Amisoft name by Ajinomoto Corp.,Tokyo, Japan. Desirably, the wetting composition contains less thanabout 3 weight percent of wetting agents and/or cleaning agents based onthe total weight of the wetting composition. More desirably, the wettingcomposition contains from about 0.01 weight percent to about 2 weightpercent of wetting agents and/or cleaning agents. Even more desirably,the wetting composition contains from about 0.1 weight percent to about0.5 weight percent of wetting agents and/or cleaning agents.

[0152] Although amino-acid based surfactants are particularly useful inthe wetting compositions of the present invention, a wide variety ofsurfactants may be used in the present invention. Suitable non-ionicsurfactants include, but are not limited to, the condensation productsof ethylene oxide with a hydrophobic (oleophilic) polyoxyalkylene baseformed by the condensation of propylene oxide with propylene glycol. Thehydrophobic portion of these compounds desirably has a molecular weightsufficiently high so as to render it water-insoluble. The addition ofpolyoxyethylene moieties to this hydrophobic portion increases thewater-solubility of the molecule as a whole, and the liquid character ofthe product is retained up to the point where the polyoxyethylenecontent is about 50% of the total weight of the condensation product.Examples of compounds of this type include commercially-availablePluronic surfactants (BASF Wyandotte Corp.), especially those in whichthe polyoxypropylene ether has a molecular weight of about 1500-3000 andthe polyoxyethylene content is about 35-55% of the molecule by weight,i.e. Pluronic L-62.

[0153] Other useful nonionic surfactants include, but are not limitedto, the condensation products of C₈-C₂₂ alkyl alcohols with 2-50 molesof ethylene oxide per mole of alcohol. Examples of compounds of thistype include the condensation products of C₁₁-C₁₅ secondary alkylalcohols with 3-50 moles of ethylene oxide per mole of alcohol, whichare commercially-available as the Poly-Tergent SLF series from OlinChemicals or the TERGITOL® series from Union Carbide, i.e. TERGITOL®25-L-7, which is formed by condensing about 7 moles of ethylene oxidewith a C₁₂-C₁₅ alkanol.

[0154] Other nonionic surfactants, which may be employed in the wettingcomposition of the present invention, include the ethylene oxide estersof C₆-C₁₂ alkyl phenols such as (nonylphenoxy)polyoxyethylene ether.Particularly useful are the esters prepared by condensing about 8-12moles of ethylene oxide with nonylphenol, i.e. the IGEPAL® CO series(GAF Corp.). Further non-ionic surface active agents include, but arenot limited to, alkyl polyglycosides (APG), derived as a condensationproduct of dextrose (D-glucose) and a straight or branched chainalcohol. The glycoside portion of the surfactant provides a hydrophilehaving high hydroxyl density, which enhances water solubility.Additionally, the inherent stability of the acetal linkage of theglycoside provides chemical stability in alkaline systems. Furthermore,unlike some non-ionic surface active agents, alkyl polyglycosides haveno cloud point, allowing one to formulate without a hydrotrope, andthese are very mild, as well as readily biodegradable non-ionicsurfactants. This class of surfactants is available from HorizonChemical under the trade names of APG-300, APG-350, APG-500, andAPG-500.

[0155] Silicones are another class of wetting agents available in pureform, or as microemulsions, macroemulsions, and the like. One exemplarynon-ionic surfactant group is the silicone-glycol copolymers. Thesesurfactants are prepared by adding poly(lower)alkylenoxy chains to thefree hydroxyl groups of dimethylpolysiloxanols and are available fromthe Dow Corning Corp as Dow Corning 190 and 193 surfactants (CTFA name:dimethicone copolyol). These surfactants function, with or without anyvolatile silicones used as solvents, to control foaming produced by theother surfactants, and also impart a shine to metallic, ceramic, andglass surfaces.

[0156] Anionic surfactants may also be used in the wetting compositionsof the present invention. Anionic surfactants useful due to their highdetergency include anionic detergent salts having alkyl substituents of8 to 22 carbon atoms such as the water-soluble higher fatty acid alkalimetal soaps, e.g., sodium myristate and sodium palmitate. A preferredclass of anionic surfactants encompasses the water-soluble sulfated andsulfonated anionic alkali metal and alkaline earth metal detergent saltscontaining a hydrophobic higher alkyl moiety (typically containing fromabout 8 to 22 carbon atoms) such as salts of higher alkyl mono orpolynuclear aryl sulfonates having from about 1 to about 16 carbon atomsin the alkyl group, with examples available as the Bio-Soft series, i.e.Bio-Soft D-40 (Stepan Chemical Co.).

[0157] Other useful classes of anionic surfactants include, but are notlimited to, the alkali metal salts of alkyl naphthalene sulfonic acids(methyl naphthalene sodium sulfonate, Petro AA, PetrochemicalCorporation); sulfated higher fatty acid monoglycerides such as thesodium salt of the sulfated monoglyceride of cocoa oil fatty acids andthe potassium salt of the sulfated monoglyceride of tallow fatty acids;alkali metal salts of sulfated fatty alcohols containing from about 10to about 18 carbon atoms (e.g., sodium lauryl sulfate and sodium stearylsulfate); sodium C₁₄-C₁₆-alphaolefin sulfonates such as the Bio-Tergeseries (Stepan Chemical Co.); alkali metal salts of sulfated ethyleneoxyfatty alcohols (the sodium or ammonium sulfates of the condensationproducts of about 3 moles of ethylene oxide with a C₁₂-C₁₅ n-alkanol,i.e., the Neodol ethoxysulfates, Shell Chemical Co.); alkali metal saltsof higher fatty esters of low molecular weight alkylol sulfonic acids,e.g. fatty acid esters of the sodium salt of isothionic acid, the fattyethanolamide sulfates; the fatty acid amides of amino alkyl sulfonicacids, e.g. lauric acid amide of taurine; as well as numerous otheranionic organic surface active agents such as sodium xylene sulfonate,sodium naphthalene sulfonate, sodium toulene sulfonate and mixturesthereof.

[0158] A further useful class of anionic surfactants includes the8-(4-n-alkyl-2-cyclohexenyl)-octanoic acids, wherein the cyclohexenylring is substituted with an additional carboxylic acid group. Thesecompounds or their potassium salts, are commercially-available fromWestvaco Corporation as Diacid 1550 or H-240. In general, these anionicsurface active agents can be employed in the form of their alkali metalsalts, ammonium or alkaline earth metal salts.

[0159] Macroemulsions and Microemulsion of Silicone Particles

[0160] The wetting composition may further comprise an aqueousmicroemulsion of silicone particles. For example, U.S. Pat. No.6,037,407, “Process for the Preparation of Aqueous Emulsions of SiliconeOils and/or Gums and/or Resins” issued Mar. 14, 2000, disclosesorganopolysiloxanes in an aqueous microemulsion. Desirably, the wettingcomposition contains less than about 5 weight percent of a microemulsionof silicone particles based on the total weight of the wettingcomposition. More desirably, the wetting composition contains from about0.02 weight percent to about 3 weight percent of a microemulsion ofsilicone particles. Even more desirably, the wetting compositioncontains from about 0.02 weight percent to about 0.5 weight percent of amicroemulsion of silicone particles.

[0161] Silicone emulsions in general may be applied to the pre-moistenedwipe by any known coating method. For example, the pre-moistened wipemay be moistened with an aqueous composition comprising awater-dispersible or water-miscible, silicone-based component that iscompatible with the activating compound in the wetting composition.Further, the wipe can comprise a nonwoven web of fibers having awater-dispersible binder, wherein the web is moistened with a lotioncomprising a silicone-based sulfosuccinate. The silicone-basedsulfosuccinate provides gentle and effective cleansing without a highlevel of surfactant. Additionally, the silicone-based sulfosuccinateprovides a solubilization function, which prevents precipitation ofoil-soluble components, such as fragrance components, vitamin extracts,plant extracts, and essential oils.

[0162] In one embodiment of the present invention, the wettingcomposition comprises a silicone copolyol sulfosuccinate, such asdisodium dimethicone copolyol sulfosuccinate and diammonium dimethiconecopolyolsulfosuccinate. Desirably, the wetting composition comprisesless than about 2 percent by weight of the silicone-basedsulfosuccinate, and more desirably from about 0.05 percent to about 0.30percent by weight of the silicone-based sulfosuccinate.

[0163] In another example of a product comprising a silicone emulsions,Dow Corning 9506 powder may also be present in the wetting composition.Dow Corning 9506 powder is believed to comprise adimethicone/vinyldimethicone cross-polymer and is a spherical powder,which is said to be useful in controlling skin oils (see “New ChemicalPerspectives,” Soap and Cosmetics, Vol. 76, No. 3, March 2000, p. 12).Thus, a water-dispersible wipe, which delivers a powder effective incontrolling skin oil, is also within the scope of the present invention.Principles for preparing silicone emulsions are disclosed in WO97/10100, published Mar. 20, 1997, the disclosure which is incorporatedby reference in its entirety.

[0164] Emollients

[0165] The wetting composition of the present invention may also containone or more emollients. Suitable emollients include, but are not limitedto, PEG 75 lanolin, methyl gluceth 20 benzoate, C₁₂-C₁₅ alkyl benzoate,ethoxylated cetyl stearyl alcohol, products marketed as Lambent waxWS-L, Lambent WD-F, Cetiol HE (Henkel Corp.), Glucam P20 (Amerchol),Polyox WSR N-10 (Union Carbide), Polyox WSR N-3000 (Union Carbide),Luviquat (BASF), Finsolv SLB 101 (Finetex Corp.), mink oil, allantoin,stearyl alcohol, Estol 1517 (Uniqema), and Finsolv SLB 201 (FinetexCorp.).

[0166] An emollient can also be applied to a surface of the articleprior to or after wetting with the wetting composition. Such anemollient may be insoluble in the wetting composition and can beimmobile except when exposed to a force. For example, a petrolatum-basedemollient can be applied to one surface in a pattern, after which theother surface is wetted to saturate the wipe. Such a product couldprovide a cleaning surface and an opposing skin treatment surface.

[0167] The emollient composition in such products and other products ofthe present invention can comprise a plastic or fluid emollient such asone or more liquid hydrocarbons (e.g., petrolatum), mineral oil and thelike, vegetable and animal fats (e.g., lanolin, phospholipids and theirderivatives) and/or a silicone materials such as one or more alkylsubstituted polysiloxane polymers, including the polysiloxane emollientsdisclosed in U.S. Pat. No. 5,891,126, issued Apr. 6, 1999 to Osborn,III. et al. Optionally, a hydrophilic surfactant may be combined with aplastic emollient to improve wettability of the coated surface. In someembodiments of the present invention, it is contemplated that liquidhydrocarbon emollients and/or alkyl substituted polysiloxane polymersmay be blended or combined with one or more fatty acid ester emollientsderived from fatty acids or fatty alcohols.

[0168] In an embodiment of the present invention, the emollient materialis in the form of an emollient blend. Desirably, the emollient blendcomprises a combination of one or more liquid hydrocarbons (e.g.,petrolatum), mineral oil and the like, vegetable and animal fats (e.g.,lanolin, phospholipids and their derivatives), with a silicone materialsuch as one or more alkyl substituted polysiloxane polymers. Moredesirably, the emollient blend comprises a combination of liquidhydrocarbons (e.g., petrolatum) with dimethicone or with dimethicone andother alkyl substituted polysiloxane polymers. In some embodiments ofthe present invention, it is contemplated that blends of liquidhydrocarbon emollients and/or alkyl substituted polysiloxane polymersmay be blended with one or more fatty acid ester emollients derived fromfatty acids or fatty alcohols. PEG-7 glyceryl cocoate, available asStandamul HE (Henkel Corp., Hoboken, N.J), can also be considered.

[0169] Water-soluble, self-emulsifying emollient oils, which are usefulin the present wetting compositions, include the polyoxyalkoxylatedlanolins and the polyoxyalkoxylated fatty alcohols, as disclosed in U.S.Pat. No. 4,690,821, issued Sep. 1, 1987 to Smith et al., hereinincorporated by reference in its entirety. The polyoxyalkoxy chainsdesirably will comprise mixed propylenoxy and ethyleneoxy units. Thelanolin derivatives will typically comprise about 20-70 suchlower-alkoxy units while the C₁₂-C₂₀-fatty alcohols will be derivatizedwith about 8-15 lower-alkyl units. One such useful lanolin derivative isLanexol AWS (PPG-12-PEG-50, Croda, Inc., New York, N.Y.). A usefulpoly(15-20)C₂-C₃-alkoxylate is PPG-5-Ceteth-20, known as Procetyl AWS(Croda, Inc.).

[0170] According to one embodiment of the present invention, theemollient material reduces undesirable tactile attributes, if any, ofthe wetting composition. For example, emollient materials, includingdimethicone, can reduce the level of tackiness that may be caused by theion-sensitive binder or other components in the wetting composition,thus serving as a detackifier.

[0171] Desirably, the wetting composition contains less than about 25weight percent of emollients based on the total weight of the wettingcomposition. More desirably, the wetting composition may comprise lessthan about 5 weight percent emollient, and most desirably less thanabout 2% emollient. More desirably, the wetting composition may containfrom about 0.01 weight percent to about 8 weight percent of emollients.Even more desirably, the wetting composition may contain from about 0.2weight percent to about 2 weight percent of emollients.

[0172] In one embodiment, the wetting composition and/or pre-moistenedwipes of the present invention comprise an oil-in-water emulsioncomprising an oil phase containing at least one emollient oil and atleast one emollient wax stabilizer dispersed in an aqueous phasecomprising at least one polyhydric alcohol emollient and at least oneorganic water-soluble detergent, as disclosed in U.S. Pat. No.4,559,157, issued Dec. 17, 1985 to Smith et al., the entirety of whichis herein incorporated by reference.

[0173] Surface Feel Modifiers

[0174] Surface feel modifiers are used to improve the tactile sensation(e.g., lubricity) of the skin during use of the product. Suitablesurface feel modifiers include, but are not limited to, commercialdebonders; and softeners, such as the softeners used in the art oftissue making including quaternary ammonium compounds with fatty acidside groups, silicones, waxes, and the like. Exemplary quaternaryammonium compounds with utility as softeners are disclosed in U.S. Pat.No. 3,554,862, issued to Hervey et al. on Jan. 12, 1971; U.S. Pat. No.4,144,122, issued to Emanuelsson et al., Mar. 13, 1979, U.S. Patent No.5,573,637, issued to Ampulski et al. Nov. 12, 1996; and U.S. Pat. No.4,476,323, issued to Hellsten et al., Oct. 9, 1984, all of which areherein incorporated by reference in their entirety. Desirably, thewetting composition contains less than about 2 weight percent of surfacefeel modifiers based on the total weight of the wetting composition.More desirably, the wetting composition contains from about 0.01 weightpercent to about 1 weight percent of surface feel modifiers. Even moredesirably, the wetting composition contains from about 0.01 weightpercent to about 0.05 weight percent of surface feel modifiers.

[0175] Fragrances

[0176] A variety of fragrances may be used in the wetting composition ofthe present invention. Desirably, the wetting composition contains lessthan about 2 weight percent of fragrances based on the total weight ofthe wetting composition. More desirably, the wetting compositioncontains from about 0.01 weight percent to about 1 weight percent offragrances. Even more desirably, the wetting composition contains fromabout 0.01 weight percent to about 0.05 weight percent of fragrances.

[0177] Fragrance Solubilizers

[0178] Further, a variety of fragrance solubilizers may be used in thewetting composition of the present invention. Suitable fragrancesolubilizers include, but are not limited to, polysorbate 20, propyleneglycol, ethanol, isopropanol, diethylene glycol monoethyl ether,dipropylene glycol, diethyl phthalate, triethyl citrate, Ameroxol OE-2(Amerchol Corp.), Brij 78 and Brij 98 (ICI Surfactants), Arlasolve 200(ICI Surfactants), Calfax 16L-35 (Pilot Chemical Co.), Capmul POE-S(Abitec Corp.), Finsolv SUBSTANTIAL (Finetex), and the like. Desirably,the wetting composition contains less than about 2 weight percent offragrance solubilizers based on the total weight of the wettingcomposition. More desirably, the wetting composition contains from about0.01 weight percent to about 1 weight percent of fragrance solubilizers.Even more desirably, the wetting composition contains from about 0.01weight percent to about 0.05 weight percent of fragrance solubilizers.

[0179] Opacifiers

[0180] Suitable opacifiers include, but are not limited to, titaniumdioxide or other minerals or pigments, and synthetic opacifiers such asREACTOPAQUE® particles (available from Sequa Chemicals, Inc., Chester,S.C.). Desirably, the wetting composition contains less than about 2weight percent of opacifiers based on the total weight of the wettingcomposition. More desirably, the wetting composition contains from about0.01 weight percent to about 1 weight percent of opacifiers. Even moredesirably, the wetting composition contains from about 0.01 weightpercent to about 0.05 weight percent of opacifiers.

[0181] pH Control Agents

[0182] Suitable pH control agents for use in the wetting composition ofthe present invention include, but are not limited to, malic acid,citric acid, hydrochloric acid, acetic acid, sodium hydroxide, potassiumhydroxide, and the like. An appropriate pH range minimizes the amount ofskin irritation resulting from the wetting composition on the skin.Desirably, the pH range of the wetting composition is from about 3.5 toabout 6.5. More desirably, the pH range of the wetting composition isfrom about 4 to about 6. Desirably, the wetting composition containsless than about 2 weight percent of a pH adjuster based on the totalweight of the wetting composition. More desirably, the wettingcomposition contains from about 0.01 weight percent to about 1 weightpercent of a pH adjuster. Even more desirably, the wetting compositioncontains from about 0.01 weight percent to about 0.05 weight percent ofa pH adjuster.

[0183] Although a variety of wetting compositions, formed from one ormore of the above-described components, may be used with the wet wipesof the present invention, in one embodiment, the wetting compositioncontains the following components, given in weight percent of thewetting composition, as shown in Table 2 below: TABLE 2 WettingComposition Components Wetting Composition Component: Weight Percent:Deionized Water about 86 to about 98 Activating compound about 1 toabout 6 Preservative Up to about 2 Surfactant Up to about 2 SiliconeEmulsion Up to about 1 Emollient Up to about 1 Fragrance Up to about 0.3Fragrance solubilizer Up to about 0.5 pH adjuster Up to about 0.2

[0184] In another embodiment of the present invention, the wettingcomposition comprises the following components, given in weight percentof the wetting composition, as shown in Table 3 below: TABLE 3 WettingComposition Components Class of Wetting Specific Wetting CompositionComposition Component Component: Component: Name: Weight Percent:Vehicle Deionized Water about 86 to about 98 Activating Sodium Chlorideabout 1 to about 6 compound (Millport Ent., Milwaukee, WI) PreservativeGlycerin, IPBC Mackstat H-66 Up to about 2 and DMDM (Mcintyre Group,Hydantoin Chicago, IL) Surfactant Acyl Glutamate CS22 Up to about 2(Ajinomoto, Tokyo, Japan) Silicone Dimethiconol and DC1785 Up to about 1Emulsion TEA (Dow Corning, (Detackifier/ Dodecylbenezene Midland, MI)Skin Sulfonate Feel agent) PEG-75 Lanolin Solulan L-575 Up to about 1Emollient (Amerchol, Middlesex, NJ Fragrance Fragrance Dragoco Up toabout 0.3 0/708768 (Dragoco, Roseville, MN) Fragrance Polysorbate 20Glennsurf L20 Up to about 0.5 solubilizer (Glenn Corp., St. Paul, MN) pHadjuster Malic Acid Up to about 0.2 to pH 5 (Haarman & Reimer, Tetrboro,NJ)

[0185] In another embodiment of the present invention, the wettingcomposition comprises the following components, given in weight percentof the wetting composition, as shown in Table 4 below: An ExemplaryWetting Composition Class of Wetting Specific Wetting CompositionComposition Component Component: Component: Name: Weight Percent: Table4 Vehicle Deionized Water About 93 Activating Sodium Chloride About 4compound Preservative Glycerin, IPBC Mackstat About 1 and DMDM H-66Hydantoin Surfactant Acyl Glutamate CS22/ECS About 1 22P SiliconeDimethiconol DC 1784/ About 0.5 Emulsion and TEA DC1785 DodecylbenezeneSulfonate Emollient PEG-75 Lanolin Solulan L- 575 About 0.25 FragranceFragrance Dragoco About 0.05 Fragrance 0/708768 Fragrance Polysorbate 20Glennsurf L20 About 0.25 solubilizer pH adjuster Malic Acid About 0.07to pH 5 Table 4a. Vehicle Deionized Water About 93 Activating Top-FloAbout 4 compound Evaporated Salt (Cargill Foods, Minneapolis, Minnesota)Preservative Glycerin, IPBC Mackstat About 1 and DMDM H-66 HydantoinSurfactant Sodium Cocoyl Hamposyl SC About 1 Gluatamate Glutamate(Hampshire Chemical, Nashua, New Hampshire) Silicone Dimethiconol and DC1784/ About 0.42 Emulsion TEA DC 1785 Dodecylbenezene SulfonateEmollient 0 Fragrance Fragrance Firmenich About 0.1 fragrance(Firmenich, Inc., Princeton, New Jersey) Fragrance Polysorbate 20Glennsurf L20 About 0.25 solubilizer pH adjuster Malic Acid About 0.07to bring the pH 5

[0186] It should be noted that the above-described wetting compositionsof the present invention may be used with any one of the above-describedion-sensitive binder compositions of the present invention. Further, theabove-described wetting compositions of the present invention may beused with any other binder composition, including conventional bindercompositions, or with any known fibrous or absorbent substrate, whetherdispersible or not.

[0187] Strength Properties

[0188] Unless otherwise specified, tensile testing is performedaccording to the following protocol. Testing of dry product should beconducted under TAPPI conditions (50% relative humidity, 73° F.) with aprocedure similar to ASTM-1117-80, section 7. Tensile tests areperformed with a constant crosshead speed tensile tester such as theThwing Albert 1256-100 tensile tester with an RSA-2 10-kg load cell.Specimens are cut to 3-inch widths and 6 inch lengths, and mountedbetween jaws with a 4-inch gauge length. The crosshead speed is 12inches per minute. Peak load (for tensile strength) and elongation atpeak load (for stretch) are measured. For cross direction (CD) tensiletests, the sample is cut in the cross direction. For machine direction(MD) tensile tests, the sample is cut in the cross direction.

[0189] Tensile tests in the dry state are reported for webs taken priorto application of the wetting composition. The machine direction drytensile strength is abbreviated as “MDDT”, and the cross direction drytensile strength as “CDDT”. The results can be reported as kg/3-in orconverted to units of g/in or g/2.54 cm.

[0190] Based on the dry weight of the specimen cut to the appropriatesize, an excess amount of wetting solution (4% saline solution with noother additives, unless otherwise specified) is applied to reach asolution add-on of about 250-400%. The wetted specimens are thenimmediately passed through an Atlas Lab Wringer (Atlas Electric DevicesCompany, Chicago, Ill. No. 10404 LW-1, no load) to uniformly distributethe solution in the sample and gently remove the excess solution toachieve a final solution add-on of about 200%. Several iterations orpasses may be needed to reach the add-on target depending on the sample.The completed, pre-moistened samples are then bagged in plastic toprevent dry-out before testing.

[0191] If an Atlas Wringer is not available the wetted sample may behand rolled using a stainless steel cylinder to uniformly distribute thesolution in the sample and gently remove the excess wetting solution.Alternatively, the wetting solution may be uniformly applied to thespecimen by hand spraying. In this case, the final solution add-on isagain measured gravimetrically only this time with the specimen placedon the balance during the application of the wetting solution. Thisalternative test method was used in a number of the Examples of thepresent application, including Examples 5-8, and 10-17.

[0192] Cross direction wet tensile tests (CDWT) or machine direction wettensile strength (MDWT) are performed as described above using thepre-moistened sample as is, after the sample has equilibrated by sittingovernight in a sealed plastic bag. Alternatively, wet tensile resultscan be measured with an MTS Synergie 200 tensile tester using theTestworks™ 3.10 for Windows software. A 1-inch wide by 4-inch long stripcan be used for testing. The gauge length between the jaws of the testdevice may be 3 inches. Testing is operated at the specified cross headspeed of 12 in/min. The peak load for each of 10 samples was measuredand the average peak load in grams per inch (g/1″).

[0193] For tests related to strength loss in a premoistened weboccurring after exposure to a new solution, a container havingdimensions of 200 mm by 120 mm and deep enough to hold 1000 ml is filledwith 700 ml of the selected soak solution. No more than 108 squareinches of sample are soaked in the 700 ml of soaking solution. Thepremoistened specimens, that have equilibrated overnight, are immersedin the soak solution and then allowed to soak undisturbed for aspecified time period (typically 1 hour). At the completion of the soakperiod, samples are carefully retrieved from the soak solution, allowedto drain, and then tested immediately as described above (i.e., thesample is immediately mounted in the tensile tester and tested, withoutbeing passed through the wringer). In cases with highly dispersiblematerials, the samples often cannot be retrieved from the soakingsolution without falling apart. The soaked tensile values for suchsamples are recorded as zero for the corresponding solution.

[0194] For the deionized soaked cross-direction wet tensile test,S-CDWT, the sample is immersed in deionized water for 1 hour and thentested. For the hard-water soaked cross-direction wet tensile test,S-CDWT-M (M indicating divalent and/or multivalent metal ions), thesample is immersed in water containing 200 ppm of Ca²⁺/Mg²⁺ in a 2:1ratio prepared from calcium chloride and magnesium chloride, soaked forone hour and then tested. For the medium hard water soakedcross-direction wet tensile test, MS-CDWT-M, the sample is immersed inwater containing 50 ppm of Ca²⁺/Mg²⁺ in a 2:1 ratio, soaked for one hourand then tested. Testing done with other time increments or soakingsolutions should be so indicated to prevent confusion with the S-CDWT orS-CDWT-M tests.

[0195] In one embodiment of the present invention, wet wipes areproduced using the above-described wetting composition in Table 3 and anair-laid fibrous material comprising about 80 weight percent of bleachedkraft fibers and about 20 weight percent of any one of theabove-described ion-sensitive binder compositions of the presentinvention, wherein the weight percentages are based on the total weightof the dry nonwoven fabric. In a further embodiment of the presentinvention, wet wipes are produced using the above-described wettingcomposition in Table 3 and an air-laid fibrous material comprising about90 weight percent of softwood fibers and about 10 weight percent of anion-sensitive binder compositions comprising acrylic acid terpolymers ora copolymer substantially free of acrylic acid monomers, wherein theweight percentages are based on the total weight of the dry nonwovenfabric. The amount of wetting composition added to the nonwoven fabric,relative to the weight of the dry nonwoven fabric in these embodiments,is desirably about 180 percent to about 240 weight percent.

[0196] Desirably, the wet wipes of the present invention possess anin-use wet tensile strength (CDWT) of at least about 100 g/in, and atensile strength of less than about 30 g/in after being soaked in waterhaving a concentration of Ca²⁺ and/or Mg²⁺ ions of about 50 ppm forabout one hour (MS-CDWT-M). More desirably, the wet wipes possess anin-use wet tensile strength of at least about 300 g/in (CDWT), and atensile strength of less than about 30 g/in after being soaked in waterhaving a concentration of Ca²⁺ and/or Mg²⁺ ions of about 50 ppm forabout one hour (MS-CDWT-M). In a further embodiment, the wet wipesdesirably possess an in-use wet tensile strength of at least about 200g/in (CDWT), and a tensile strength of less than about 20 g/in afterbeing soaked in water having a concentration of Ca²⁺ and/or Mg²⁺ ions ofabout 200 ppm for about one hour (S-CDWT-M). Even more desirably, thewet wipes possess an in-use wet tensile strength of at least about 300g/in, and a tensile strength of less than about 20 g/in after beingsoaked in water having a concentration of Ca²⁺ and/or Mg²⁺ ions of about200 ppm for about one hour (S-CDWT-M).

[0197] Desirably, the wet wipes treated with the binder material of thepresent invention including the acrylic acid terpolymer possess anin-use wet tensile strength of at least about 100 g/in for a 1 inchwidth sample in the cross machine direction when soaked with about 10%to about 400% by weight wet wipes solution containing more than about0.3% by weight monovalent ion (NaCl) concentration and a tensilestrength of less than about 30 g/in after being soaked in deionizedwater for about one hour. More desirably, the wet wipes treated with thebinder material of the present invention including the acrylic acidterpolymer possess an in-use tensile strength of at least about 200 g/infor a 1 inch width sample in the cross machine direction when soakedwith about 10% to about 400% by weight wet wipes solution containingmore than about 0.3% by weight monovalent ion (NaCl) concentration and atensile strength of less than about 30 g/in after being soaked indeionized water for about one hour.

[0198] In a further embodiment, the wet wipes treated with the bindermaterial of the present invention including the sulfonate anion modifiedacrylic acid terpolymer desirably possess an in-use tensile strength ofat least about 200 g/in for a 1 inch width sample in the cross machinedirection when soaked with about 10% to about 400% by weight wet wipessolution containing more than about 1% by weight monovalent ion (NaCl)concentration and a tensile strength of less than about 30 g/in afterbeing soaked in water having a concentration of Ca²⁺ and/or Mg²⁺ ions ofabout 50 ppm for about one hour. Even more desirably, the wet wipestreated with the binder material of the present invention including thesulfonate anion modified acrylic acid terpolymer possess an in-usetensile strength of at least about 200 g/in for a 1 inch width sample inthe cross machine direction when soaked with about 10% to about 400% byweight wet wipes solution containing more than about 1% by weightmonovalent ion (NaCl) concentration and a tensile strength of less thanabout 30 g/in after being soaked in water having a concentration of Ca²⁺and/or Mg²⁺ ions of about 200 ppm for about one hour.

[0199] Products with higher basis weights or wet strengths thanflushable wet wipes may have relatively higher wet tensile strength. Forexample, products such as pre-moistened towels or hard-surface cleaningwipes may have basis weights above about 70 gsm, such as from about 80gsm to about 150 gsm. Such products can have CDWT values of about 500g/in or greater, with S-CDWT values of about 150 g/in or less, moredesirably about 100 g/in or less, and most desirably about 50 g/in orless, with similar ranges possible for S-CDWT-M.

[0200] Dispersibility

[0201] Prior efforts to measure dispersibility of webs, whether dry orpremoistened, have commonly relied on systems in which the web wasexposed to shear while in water, such as measuring the time for a web tobreak up while being agitated by a mechanical mixer. The constantexposure to shear offers a somewhat unrealistic and overly optimistictest for products designed to be flushed in a toilet, where the level ofshear is weak and extremely brief. Once the product has passed throughthe neck of the toilet and entered a septic tank, shear rates may benegligible. Further, the product may not be fully wetted with water fromthe toilet bowl when it is flushed, or rather, there may not have beenadequate time for the wetting composition of the product to have beenreplaced with the water of the toilet bowl when the momentary shear offlushing is applied. Thus, previous measurements of dispersibility couldsuggest that a product is dispersible when, in fact, it may be poorlysuited for septic and sewer systems.

[0202] For a more realistic appraisal of dispersibility, it is believedthat a relatively static measure is needed to better simulate the lowshear that real products will experience once they have become fullywetted with water from the toilet. Thus, a test method fordispersibility has been developed which does not rely on shear and whichprovides an improved means of assessing suitability of a product for aseptic system. In this method, the tensile strength of a product ismeasured in its original, wetted form (the CDWT measurement describedabove) and after the product has been soaked in a second solution forone hour (either the S-CDWT or S-CDWT-M test). The second solution canbe either deionized water for determination of the “DeionizedDispersibility” value or hard water (according to the S-CDWT-M test) fordetermination of the “Hard Water Dispersibility” value. In either case,the Dispersibility is defined as (1 minus the ratio of thecross-direction wet tensile strength in the second solution divided bythe original cross-direction wet tensile strength)*100%. Thus, if apre-moistened wipe loses 75% of its CD wet tensile strength aftersoaking in hard water for one hour, the Hard Water Dispersibility is(1−0.25)*100%=75%. The articles of the present invention desirably havea Deionized Dispersibility of about 80% or greater, more desirably about90% or greater, and more desirable still about 95% or greater, and canhave a Deionized Dispersibility of about 100%. The articles of thepresent invention desirably have a Hard Water Dispersibility of about70% or greater, more desirably about 80% or greater, more desirablyabout 90% or greater, and desirably have a Deionized Dispersibility ofabout 100%.

[0203] As before, it is desirable for the water dispersible fibrousfabric of the present invention to disperse in water after no more thanabout 60 minutes, more desirably after no more than about 20 minutes,and more desirably to disperse in water after no more than about 10minutes. Furthermore, it also desirable that wherein after up to about60 minutes, more desirably after up to about 20 minutes of exposure towater that the fibrous material of the present invention break up intomultiple pieces each having an average size of less than about 50%relative to its pre-dispersed size, more desirably into multiple pieceseach having an average size of less than about 40% relative to itspre-dispersed size, and even more desirably into multiple pieces eachhaving an average size of less than about 30% relative to itspre-dispersed size.

[0204] Method of Making Wet Wipes

[0205] The pre-moistened wipes of the present invention can be made inseveral ways. In one embodiment, the ion-sensitive polymer compositionis applied to a fibrous substrate as part of an aqueous solution orsuspension, wherein subsequent drying is needed to remove the water andpromote binding of the fibers. In particular, during drying, the bindermigrates to the crossover points of the fibers and becomes activated asa binder in those regions, thus providing acceptable strength to thesubstrate. For example, the following steps can be applied:

[0206] 1. Providing an absorbent substrate that is not highly bonded(e.g., an unbonded airlaid, a tissue web, a carded web, fluff pulp,etc.).

[0207] 2. Applying an ion-sensitive polymer composition to thesubstrate, typically in the form of a liquid, suspension, or foam.

[0208] 3. Applying a co-binder polymer to the substrate.

[0209] 4. Drying the substrate to promote bonding of the substrate. Thesubstrate may be dried such that the peak substrate temperature does notexceed about 200° C., or about 180° C., or about 160° C., or about 140°C., or about 120° C., about 110° C., or about 100° C. In one embodiment,the substrate temperature does not exceed about 80° C. or about 60° C.

[0210] 5. Applying a wetting composition to the substrate.

[0211] 6. Placing the wetted substrate in roll form or in a stack andpackaging the product.

[0212] Application of the co-binder polymer can be done simultaneouslywith application of the binder composition by previously mixing the two,or the co-binder polymer can be added before or after the binder isapplied. The other steps are desirably conducted in the order shownabove.

[0213] Application of the ion-sensitive polymer composition to thesubstrate can be by means of spray; by foam application; by immersion ina bath; by curtain coating; by coating and metering with a wire-woundrod; by passage of the substrate through a flooded nip; by contact witha pre-metered wetted roll coated with the binder solution; by pressingthe substrate against a deformable carrier containing the ion-sensitivepolymer composition such as a sponge or felt to effect transfer into thesubstrate; by printing such as gravure, inkjet, or flexographicprinting; and any other means known in the art.

[0214] In the use of foams to apply a binder or co-binder polymer, themixture is frothed, typically with a foaming agent, and spread uniformlyon the substrate, after which vacuum is applied to pull the froththrough the substrate. Any known foam application method can be used,including that of U.S. Pat. No. 4,018,647, “Process for the Impregnationof a Wet Fiber Web with a Heat Sensitized Foamed Latex Binder,” issuedApr. 19, 1977 to Wietsma, the entirety of which is herein incorporatedby reference. Wietsma discloses a method wherein a foamed latex isheat-sensitized by the addition of a heat-sensitizer such as functionalsiloxane compounds including siloxane oxyalkylene block copolymers andorganopolysiloxanes. Specific examples of applicable heat-sensitizersand their use thereof for the heat sensitization of latices aredescribed in the U.S. Pat. Nos. 3,255,140; 3,255,141; 3,483,240 and3,484,394, all of which are incorporated herein by reference in theirentirety. The use of a heat-sensitizer is said to result in a producthaving a very soft and textile-like hand compared to prior methods ofapplying foamed latex binders.

[0215] The amount of heat-sensitizer to be added is dependent on, interalia, the type of latex used, the desired coagulation temperature, themachine speed and the temperatures in the drying section of the machine,and will generally be in the range of about 0.05 to about 3% by weight,calculated as dry matter on the dry weight of the latex; but also largeror smaller amounts may be used. The heat sensitizer can be added in suchan amount that the latex will coagulate far below the boiling point ofwater, for instance at a temperature in the range of about 35° C. toabout 95° C., or from about 35° C. to about 65° C.

[0216] Without wishing to be bound by theory, it is believed that adrying step after application of the binder solution and beforeapplication of the wetting composition enhances bonding of a fibroussubstrate by driving the binder to fiber crossover points as moisture isdriven off, thus promoting efficient use of the binder. However, in analternative method, the drying step listed above is skipped, and theion-sensitive polymer composition is applied to the substrate followedby application of the wetting composition without significantintermediate drying. In one version of this method, the ion-sensitivepolymer composition selectively adheres to the fibers, permitting excesswater to be removed in an optional pressing step without a significantloss of the binder from the substrate. In another version, nosignificant water removal occurs prior to application of the wettingcomposition. In yet another alternative method, the ion-sensitivepolymer composition and the wetting composition are appliedsimultaneously, optionally with subsequent addition of salt or otheractivating compounds to activate or further activate the binder.

[0217] The present invention is further illustrated by the followingexamples, which are not to be construed in any way as imposinglimitations upon the scope thereof. On the contrary, it is to be clearlyunderstood that resort may be had to various other embodiments,modifications, and equivalents thereof which, after reading thedescription herein, may suggest themselves to those skilled in the artwithout departing from the spirit of the present invention and/or thescope of the appended claims.

EXAMPLES

[0218] As used herein, the “thickness” of a web is measured with a 3-inacrylic plastic disk connected to the spindle of a Mitutoyo DigimaticIndicator (Mitutoyo Corporation, 31-19, Shiba 5-chome, Minato-ku, Tokyo108, Japan) and which delivers a net load of 0.05 psi to the samplebeing measured. The Mitutoyo Digimatic Indicator is zeroed when the diskrests on a flat surface. When a sample having a size at least as greatas the acrylic disk is placed under the disk, a thickness reading can beobtained from the digital readout of the indicator. Water-dispersiblesubstrates of the present invention can have any suitable thickness,such as from about 0.1 mm to about 5 mm. For wet wipes, thicknesses canbe in the range of about 0.2 mm to about 1 mm, more desirably from about0.3 mm to about 0.7 mm. Thickness can be controlled, for example, by theapplication of compaction rolls during or after web formation, bypressing after binder or wetting composition has been applied, or bycontrolling the tension of winding when forming a roll good.

[0219] The use of the platen method to measure thickness gives anaverage thickness at the macroscopic level. Local thickness may vary,especially if the product has been embossed or has otherwise been givena three-dimensional texture.

Example 1

[0220] Preparation of Sulfonate Anion Modified Acrylic Acid Terpolymer

[0221] An sulfonate anion modified acrylic acid terpolymer was producedusing the polymerization procedure outlined in Example 1 of U.S. patentapplication Ser. No. 09/564,212 (a co-pending application assigned toKimberly Clark entitled “Ion-Sensitive, Water-Dispersible Polymers, AMethod Of Making Same And Items Using Same”), filed May 4, 2000. Thefollowing monomers were used: acrylic acid (43.3 g, 0.60 mol), AMPS(10.7 g, 0.052 mol), butyl acrylate (31.9, 0.245 mol), and 2-ethylhexylacrylate (19.1, 0.105 mol) were dissolved in 55 g of acetone/water(70/30) mixture. An initiator, 2,2-azobisisobutyronitrile (AIBN) (0.51g, 3.1×10⁻³ mol), was dissolved in 20 ml of acetone. NAOH (2.1 g, 0.052mol) in 20 ml of water was added at room temperature to neutralize theAMPS component in the samples. The desired composition of the resultingterpolymer contained 5.0 mole % NaAMPS, 60 mole % AA, 24.5 mole % BA and10.5 mole % EHA. Additional NaOH may desirably be added to raise thepolymer solution's pH to 3.9 to 4.5.

Example 2

[0222] Preparation of an Acrylic Acid Terpolymer

[0223] An acrylic acid terpolymer was produced using the polymerizationprocedure outlined in Example 2 of U.S. Pat. No. 5,312,883. Thefollowing monomers were used: acrylic acid (50 g, 0.60 mol), butylacrylate (25 g, 0.20 mol), and 2-ethylhexyl acrylate (25 g, 0.14 mol).The polymer was neutralized with 0.1 mole sodium hydroxide.

Example 3

[0224] Preparation of Ion-sensitive Polymer Formulation

[0225] The polymers prepared in Example 1 and Example 2 above werecombined with Dur-O-Set® RB to form the ion-sensitive polymerformulations of the present invention. The polymer formulations wereprepared as shown in Table 5 below. TABLE 5 Ion-Sensitive PolymerFormulations % Terpolymer % Modified Terpolymer Sample (Example 2)(Example 1) % EVA  1 85.0 0.0 15.0  2 0.0 85.0 15.0  3 65.0 0.0 35.0  40.0 65.0 35.0  5 95.0 0.0 5.0  6 0.0 95.0 5.0  7 55~o 0.0 45.0  8 0.055.0 45.0  9 75.0 0.0 25.0 10 0.0 75.0 25.0

Example 4

[0226] Dispersibility of Ion-sensitive Polymer Formulation

[0227] The sensitivity of the polymer formulations of Example 3 todivalent cations present in hard water were measured. Samples 1-10 ofExample 3 are placed in a number of CaCl₂ solutions with a Ca²⁺concentration varying from <10 to 200 ppm. Following soaking for anhour, the dispersibility of each polymer is noted. The dispersibilityresults (expressed in percentages) are given below in Table 6. TABLE 6Dispersibility Results Dispersibility in Ca²⁺ Sample <10 ppm 50 ppm 100ppm 200 ppm  Sample 1 100  94  78 12  Sample 2 100 100  98 91  Sample 3100  60  36  2  Sample 4  99 100  97 90  Sample 5 100  97  88 19  Sample6 100 100  99 90  Sample 7  89  42  31  0  Sample 8 100  96  96 90 Sample 9 100  73  78  7 Sample 10 100 100 100 90

[0228] In every case the film cast from the blend containing NaAMPS ismore dispersible than the film containing the acrylic acid terpolymer,especially as the calcium ion concentration increases.

Example 5

[0229] A substrate in the form of an airlaid web was prepared on acommercial airlaid machine having a width of 66.5 inches. A DanWebairlaid former with two forming heads was used to produce substrateshaving basis weights of about 60 gsm. Weyerhaeuser CF405 bleachedsoftwood kraft fiber in pulp sheet form was used and fiberized in ahammermill, then formed into an airlaid web on a moving wire at a speedof 200 to 300 feet per minute. The newly formed web was densified byheated compaction rolls and transferred to a second wire, where the webwas humidified with an atomized spray of water applying an estimated 5%moisture add on level immediately prior to a second heated compactionroll to further density the web. The web was then transferred to an ovenwire and sprayed on the top side with ion-sensitive polymer formulationmixture on the exposed surface of the web, applying 10% ion-sensitivepolymer formulation solids relative to the dry fiber mass of the web.

[0230] The ion-sensitive polymer formulation mixture comprised water asthe carrier with 12% binder solids, wherein the binder comprised 75%SSB-4 as the ion-sensitive polymer formulation and 25% Rhoplex® NW-1715Klatex emulsion (Rohm and Haas Corp.) as the co-binder polymer.

[0231] Spray was applied with a series of Quick Veejet® nozzles, NozzleNo. 730077, manufactured by Spraying Systems Co. (Wheaton, Ill.),operating at 95 psi. A spray boom over the web provided 13 such nozzleson 5.5-inch centers with a tip-to-wire distance of 8 inches. Thisarrangement yields 100% overlap of spray cones for the ion-sensitivepolymer formulation solution of this trial.

[0232] After the web was sprayed, it was carried into an oven withthrough-flow of air at about 225° C. to dry the binder solution. The webthen was transferred onto the underside of another oven wire, upon whichit passed over another spray boom where more ion-sensitive polymerformulation solution was applied to the bottom side of the web to addanother 10 weight percent solids relative to the dry fiber mass of theweb. The web then passed through two successive dryer units wherethrough-air drying with air at about 225° C. completed drying of theweb. The pressure differential across the web was approximately 10inches of water. The length of the three dryer sections, from first tothird, respectively, was about 9, 10, and 6 feet.

[0233] The thickness of the web after drying was 1.14 mm (this number,like other physical properties reported here, can vary depending on thefibers, basis weight, and so forth). The machine direction dry tensile(MDDT) strength of the web was measured at 4.59 kg/3-in. The crossdirection dry tensile (CDDT) strength of the web was measured at 3.82kg/3-in with a CD stretch of 8.98%.

[0234] The dried and treated web was then trimmed to 60 inches width,reeled and later slit into 4-inch wide rolls, which were then handtreated with wetting composition and formed into coreless rolls suitablefor use as a pre-moistened bath wipe. The wetting composition wasuniformly applied on one side of the 4-inch wide web prior to reelingthe web into rolls suitably sized for use. The wetting composition was 4weight percent NaCl in deionized water.

[0235] The cross direction wet tensile (CDWT) at 4 weight percent salinewas measured at 0.76 kg/3-in. The Soaked CDWT strength was effectively0, as was the Soaked CD Stretch, meaning the sheet was fullydispersible.

Example 6

[0236] The sheet formed was identical to that of Example 5 except thatthe fibers in the airlaid web were 75% softwood kraft and 25% PETfibers. The thickness of the web after drying was 1.35 mm. The machinedirection dry tensile (MDDT) strength of the web was measured at 3.87kg/3-in. The cross direction dry tensile (CDDT) strength of the web wasmeasured at 2.84 kg/3-in with a CD stretch of 11.31%. The crossdirection wet tensile (CDWT) at 4% saline was measured at 0.82 kg/3-in.The Soaked CDWT strength was effectively 0, as was the Soaked CDStretch.

Example 7

[0237] Additional examples were conducted according to Example 5, withthe exception that Rovene® latex emulsion was used as the co-binderpolymer and the basis weight and fiber composition varied as shown inTable 7. The Soaked CDWT results were all 0, indicating a complete lossof tensile strength. Other results are shown in Table 7, where Pulp/PETdesignates the ratio of softwood to synthetic fibers in the substrate,BW is the basis weight in gsm, TH is the thickness in mm, and S-CDWT-Mis the one-hour soak CD wet tensile test for a sample soaked in watercontaining 200 ppm of Ca²⁺ /Mg²⁺ in a 2:1 ratio. TABLE 7 Measurementsfor Examples 3A-3F. MDDT CDDT CDWT S-CDWT-M Run Pulp/PET BW (gsm) Thick.(mm) (kg/3-in) (kg/3-in) (kg/3-in) (kg/3-in) 3A 110/0  60.3 1.18 5.444.12 0.69 0 3B 85/15 62.9 1.25 4.68 4.23 0.66 0 3C 75/25 55.6 1.04 5.484.06 0.66 0 3D 75/25 59.3 1.19 4.87 3.96 0.81 0.17 3E 75/25 60.7 1.484.41 3.51 0.79 0.12 3F 85/15 62.7 1.46 4.60 3.82 0.76 0

[0238] The S-CDWT-M values (soaked wet tensile in hard water) werenon-zero for two trials with 25% PET fibers, suggesting that higheramounts of synthetic fibers can begin to compromise waterdispersibility.

Example 8

[0239] A pre-moistened wipe was made similar to that of Example 5,except that the co-binder polymer was a modified Elite® latex emulsionsubstantially free of crosslinking agents provided by National Starch.The basis weight of the web was 61.35, the thickness 1.21 mm, the MDDT5.09 kg/3-in, the MD stretch 7.89%, the CDDT 3.90 kg/3-in, the CDstretch 9.50%, the CDWT in 4% saline 0.78 kg/3-in, the CDWT stretch32.96%, and the residual strengths after one hour in both deionizedwater (S-CDWT) and hard water (S-CDWT-M) were 0 kg/3-in.

Example 9

[0240] Binder Specifications

[0241] A variety of ion-sensitive binders were prepared comprising wasprepared acrylic acid (M), butacrylic acid (BA), 2-ethylhexyl-acrylicacid (2-EHA), and AMPS, with mole percents and molecular weights shownin Table 8: TABLE 8 Ion-sensitive binders comprising AMPS SSB Molepercent of monomers: Code MW × 10⁻⁶ AA BA 2-EHA AMPS A 1.54 60 24.5 10.55 B 1.32 60 24.5 10.5 5 C 0.604 60 24.5 10.5 5 D 0.548 60 24.5 10.5 5 E0.609 60 24.5 10.5 5 F 0.545 60 24.5 10.5 5 G 1.21 62 24.5 8.5 5 H 0.7960 24.5 10.5 5 I 0.916 60 24.5 10.5 5 J 0.71 60 24.5 10.5 5 K 0.786 6024.5 10.5 5 L 0.845 60 24.5 10.5 5 M 0.640 60 24.5 10.5 5 N 0.800 6024.5 10.5 5 O 0.635 60 24.5 10.5 5 P 0.610 60 24.5 10.5 5 Q 0.575 6024.5 10.5 5 R 0.638 60 24.5 10.5 5 T 0.609 60 25.5 10.5 4

[0242] The binder was prepared according to the methods of Example 1,but scaled up as a batch process capable of producing several hundredgallons per batch.

Example 10

[0243] A variety of binder/co-binder combinations were prepared, asdescribed below, using the salt-sensitive binders of Table 8 andco-binders as shown in Table 9 which are not self-crosslinkable. TABLE 9Latex co-binders that are not self-crosslinkable. Co-binder ID Co-binderManufacturer 1 Dur-O-Set ® RB National Starch 2 Rhoplex ® NW-1715K Rohmand Haas 3 Rovene ® 4817 Mallard Creek

[0244] Using the methods described in Example 5, airlaid substrates weremade from bleached kraft fibers. The substrate was hand wetted with a 4%NaCl solution and tested using the methods described. All substrateswere comprised of wood pulp (CF405) and binder. Results are shown inTable 10, where the binder mixture consistently comprised 75% of asalt-sensitive binder selected from Table 8 and 25% of a co-binderselected from Table 9. The binder/co-binder column refers to the binderand co-binders listed in Table 8 and 9, respectively. For example, “A/1”refers to a mixture of SSB Code A in Table 8 and co-binder 1 of Table 9.TABLE 10 Tensile data for various binder systems. % Binder/ SSB BWThick. CDWT S-CDWT S-CDWT-M S-CDWT-M3 Binder Cob. MW × 10⁻⁶ (gsm) (mm)(kg/3-in) (kg/3-in) (kg/3-in) 3 hrs (kg/3-in) 16.7 A/1 1.54 71.3 1.460.990 0 0.330 0.180 20 B/1 1.32 63.3 1.25 1.242 0.163 0.470 0.310 20 B/11.32 66.6 1.46 1.040 0 0.230 0.550 20 G/1 1.21 62.2 1.20 1.002 0 0.270 020 H/1 0.79 63.1 1.3 1.070 0 0 0 16.7 C/1 0.604 73.6 1.59 0.750 0 0 0 20C/1 0.604 71.2 1.5 0.900 0 0 0 20 C/1 0.604 61.1 1.28 1.140 0 0 0 20 D/10.548 62.5 1.32 0.900 0 0 0

[0245] As seen in Table 10, nearly all of the substrates have lost morethat 80% of their tensile strength after soaking in deionized water for1 hour (S-CDWT). The substrates have lost more that 60% of theirstrength (S-CDWT-M) after soaking for 1 hour in a solution of 200 ppm ofdivalent cations (Ca²⁺/Mg²⁺ 2:1). In particular, for the runs shown inTable 10, the samples completely lost their strength in 1 hour in the200 ppm solution when the molecular weight of the salt sensitive binderwas less than 1,200,000. After 3 hours of soak time in the 200 ppmdivalent cation solution, the SSBs with high molecular weight havegenerally lost more of their strength, but may still have non-zerotensile strength.

Example 11

[0246] Different co-binders from Table 9 were blended with thesalt-sensitive binder Code F from Table 8. The binder blend was thenapplied using the methods described in Example 5 to create the airlaidsubstrates listed in Table 11. In each case, 20% binder solids wereapplied to the substrate in a blend of 75% SSB/25% co-binder TABLE 11Tensile data for various co-binder systems. Binder/ Co-binder CDWTS-CDWT S-CDWT-M Co-binder Used BW (gsm) Thick, (mm) (kg/3-in) (kg/3-in)(kg/3-in) F/1 Dur-O- 59.77 1.06 0.735 0 0 Set ® RB F/2 Rhoplex ® 60.831.14 0.758 0 0 F/3 Rovene ® 60.28 1.18 0.687 0 0

[0247] Under similar run conditions, all three co-binders performcomparably. All of the substrates have lost their tensile strength(S-CDWT-M) in the 200 ppm divalent cation solution independent ofco-binder type.

Example 12

[0248] Additional samples were prepared according to Example 11 above,except that 15 weight % of the fiber blend consisted of 6-mm, 3 deniercrimped PET fibers (KoSa). Different co-binders from Table 9 wereblended with the salt-sensitive binder Code F from Table 8. The binderblend was then applied using the methods described in Example 5 tocreate the airlaid substrates whose properties are listed in Table 12.In each case, 20% binder solids were applied to the substrate in a blendof 75% SSB/25% co-binder. The properties of these substrates weremeasured after wetting with a 4% NaCl solution. All three co-bindersperform comparably. All of the substrates have lost their tensilestrength in 200 ppm divalent cation solution independent of co-bindertype. Compared to the parallel results in Example 11, incorporation ofthe synthetic fibers impart a slight to modest strength improvement(CDWT) and a modest increase in dry bulk. TABLE 12 Data for substrateswith PET fibers and various co-binders. Binder/ Co-binder CDWT S-CDWTS-CDWT-M Co-binder Used BW (gsm) Thick (mm) (kg/3-in) (kg/3-in)(kg/3-in) F/1 Dur-O- 63.32 1.31 0.782 0 0 Set ® RB F/2 Rhoplex ® 62.071.35 0.820 0 0 F/3 Rovene ® 62.90 1.25 0.660 0 0

Example 13

[0249] Additional examples were conducted according to Example 11 withincreasing amounts of synthetic fiber being added to the fiber blend.Either a 6 mm crimped PET fiber (KoSa) or a 6 mm, crimped 2.4 dtex,TENCEL® fiber (Acordis) was used as noted in Table 13 below. The binderblend was a constant blend of 75% SSB and 25% co-binder. TABLE 13 Datafor substrates with PET and TENCEL ® fibers and various co-binders.Pulp/ Synth. Binder Binder/ BW Thick. CDWT S-CDWT S-CDWT-M Synth. Type %Co-binder (gsm) (mm) (kg/3-in) (kg/3-in) (kg/3-in) 100/0  None 20% F/360.28 1.18 0.687 0 0 85/15 PET 6 mm 20% F/3 62.90 1.25 0.660 0 0 75/25PET 6 mm 20% F/3 59.32 1.19 0.805 0 0.170 75/25 PET 6 mm 20% F/3 60.651.48 0.790 0 0.120 85/15 PET 6 mm 20% F/3 62.67 1.46 0.757 0 0 85/15TENCEL ® 19% E/2 58.3 1.08 0.969 0 0 -6 mm 75/25 TENCEL ® 19% E/2 59.21.09 1.080 0 0.127 -6 mm

[0250] The soaked CDWT tensiles in 200 ppm of divalent cation arenon-zero for those trial combinations with 25% synthetic fiber (PET orlyocell), suggesting that higher amounts can begin to compromise waterdispersibility.

Example 14

[0251] All substrates were prepared according to the methods describedin Example 13. All substrates were comprised of the fiber blend noted inTable 14 with 20% binder in the sheet and Dur-O-Set® RB serving as theco-binder. Synthetic fibers were crimped and either 6 mm, 3 denier PET(KoSa) or 6 or 8 mm, 1.7 dtex TENCEL® (Acordis). TABLE 14 Data forsubstrates with various fibers and binders. % Syn. Syn. Binder/ BWThick. MDDT CDDT CDWT S-CDWT S-CDWT-M Code Fiber Fiber Cob. (gsm) (mm)(kg/3-in) (kg/3-in) (kg/3-in) (kg/3-in) (kg/3-in) 2701 0 None F/1 61.31.19 4.65 3.50 0.738 0 0 2702 15 PET F/1 63.3 1.31 3.63 3.00 0.782 0 02714 15 L-1.7-6 F/1 61.8 1.33 5.50 4.22 0.768 0 0 2715 15 L-1.7-8 F/163.7 1.47 5.47 4.69 0.842 0 0 2716 0 None J/1 65.5 1.11 5.91 4.39 1.1930 0 2717 15 L-1.7-8 J/1 61.4 1.02 6.87 5.34 1.512 0 0.200 3010 0 NoneR/1 61.1 0.80 7.17 6.30 1.710 0 0 3015 15 PET R/1 62.23 0.86 5.85 5.111.769 0 0.070 3016 5 L-1.7-8 R/1 60.63 0.79 8.64 8.00 2.620 0 0.170

[0252] The examples of Table 14 suggest that that synthetic fiberlength, weight and web compaction in combination can affect thedispersibility of the product as indicated by its S-CDWT-M value.

[0253] While not wishing to be bound by theory, it is believed that theuse of 8 mm lyocell fibers provided fibers which had sufficient lengthso as to allow or enable some of the fibers to become sufficientlyengage or overlap with the others so as to provide some strengthcharacteristics yet not be so engaged with the other fibers so as toadversely effect the dispersibility of the fabric.

Example 15

[0254] The substrates listed in Table 15 were prepared, wetted with 4%NaCl solution, and tested according to the methods described in Example14. Each substrate was comprised of the fiber blend noted and 17% binder(using 75/25 blends of SSB binder (see Table 8) and Dur-O-Set® RB latexco-binder (National Starch).) The SSB binder comprised 60 mole percentacrylic acid (AA), 24.5 mole percent butacrylic acid (BA), 10.5 molepercent 2-ethylhexyl-acrylic acid (2-EHA), and 5 mole percent AMPS; thepolymer was neutralized to a pH of about 4.2. The basis weight wasgenerally held constant to about 60 gsm. The thickness or caliper of theweb was generally held constant. TABLE 15 Data for substrates withvarious amounts and lengths of synthetic fiber. Binder/ % Syn. Syn. BWThick. 4% NaCl 4% NaCl 4% NaCl Code Cob. Fiber Fiber (gsm) (mm) MDWT(g/in) Stretch (%) CD Tear (g) 2 (Control) 75/25 0 58.5 0.88 287 (9.5)30.72 (2.78) 59.1 (4.55) 4 75/25 10 L-6 mm- 62.2 0.74 206 (17.6) 28.86(4.46) 68.5 (8.50) 1.7 dtex 6 75/25 10 L-8 mm- 60.1 0.93 365 (16.8)30.70 (2.60) 84.5 (8.64) 1.7 dtex 6A 75/25 15 L-8 mm- 57.3 0.85 328(75.7) 25.93 (7.22) 85.2 (9.16) 1.7 dtex 6B 75/25 20 L-8 mm- 56.8 0.86409 (14.8) 31.40 (1.71) 90.6 (7.23) 1.7 dtex

[0255] In Table 15, each data point represents an average of 10 sampleswith the mean values expressed and the standard deviation (sigma)expressed in parenthesis following the mean value.

[0256] As the length and quantity of the synthetic fiber increases thereis a noticeable increase in the MDWT. These examples suggest thatincreasing the amount and quantity of synthetic fiber can providedesired wet strength without compromising the dispersibility of theproduct.

Example 16

[0257] Samples were made as in Example 5 using 75/25 blends of SSBbinder (see Table 8) and Dur-O-Set® RB co-binder (co-binder 1 of Table9), according to the information in Table 16 below. Each sample was handwetted with the composition identified in Table 4a. The binder solutionhad about 15 weight percent binder solids. Codes 1900 and 2300 included0% lyocell fibers. Codes 1910 and 2310 contained 10% lyocell fibers (8mm, 1.7 dtex). Code 1900 and 1910 contained 19% binder. Codes 2300 and2310 contained 23% binder. The samples were made at a line speed of 365feet per minute. TABLE 16 Data for substrates with various syntheticamounts. # of data points BW Caliper Density MDWT MDWT used to produceCode (gsm) (mm) (g/cc) (g/inch) Stretch (%) sample results 1900 62.70.84 0.075 298 28.9 16 1910 60.6 0.93 0.065 400 29.1 32 2300 65.6 0.840.078 434 28.9 32 2310 63.9 0.88 0.073 599 31.5 40

[0258] The results of Table 16 shows that the amount of binder in theweb can be manipulated and result in an increased strength where allother factors being equal. Table 16 also shows that the percentage of 8mm TENCEL® fibers (Acordis) in the web can be manipulated and result inan increased strength where all other factors being equal. Asillustrated the addition of lyocell increases the basesheet MDWT byabout 130 g/inch. The amount of the increase was unexpected.

Example 17

[0259] Samples were made as in Example 5 using 75/25 blends of SSBbinder (see Table 8) and Dur-O-Set® RB co-binder (co-binder 1 of Table9), according to the information in Table 17 below. The binder solutionhad about 15 weight percent binder solids. Codes 3900 and 3901 wereperformed without the addition of synthetic fibers, whereas Code 3910included 8 mm, 1.7 dtex lyocell fibers. Tensile results in Table 17 showgood dispersibility over a range of product conditions as well as asignificant increase in both MD and CD tensile strengths where 8 mmsynthetic fibers are included in the substrate. TABLE 17 TensileStrength. 4% 4% NaCl 1 hour BW Caliper % % Actual Actual NaCl MDWT CDWTMDWT Code target target binder lyocell BW Caliper MDWT Stretch (4%) MDDTSoak DI 3900 65 1.2 20% 0% 65.0 1.16 439 31 323 1628 0 3901 65 0.8 20%0% 66.9 0.79 469 30 385 2212 0 3909 65 0.8 20% 10% 66.5 0.83 717 28 5542798 12

[0260] It should be understood, of course, that the foregoing relatesonly to certain disclosed embodiments of the present invention and thatnumerous modifications or alterations may be made therein withoutdeparting from the spirit and scope of the invention as set forth in theappended claims.

What is claimed is:
 1. A water dispersible fibrous fabric comprising: a fibrous substrate, wherein less than about 20% of the fibers comprising the fibrous substrate have a length of about 6-10 mm; and a water-soluble binder; wherein said binder is an ion-sensitive composition comprising a sulfonate anion modified acrylic acid terpolymer and a non-crosslinking poly(ethylene-vinyl acetate), wherein the composition is insoluble in a neutral salt solution containing at least about 0.3 weight percent salt, said salt comprising one or more monovalent ions; wherein said binder comprises less than about 25% by weight of said fibrous fabric and said fibrous substrate comprising more than about 75% by weight of said fibrous fabric; and wherein the fabric is dispersible in an aqueous environment containing up to about 200 ppm of one or more divalent and/or multivalent ions.
 2. The water dispersible fibrous fabric of claim 1, wherein said binder comprises from about 10-15% by weight of said fibrous fabric and said fibrous substrate comprising from about 85-90% by weight of said fibrous fabric.
 3. The water dispersible fibrous fabric of claim 1, wherein said fibers have a length of about 7-9 mm.
 4. The water dispersible fibrous fabric of claim 1, said fibers have a length of about 8 mm.
 5. The water dispersible fibrous fabric of claim 1, wherein said binder comprises from about 5% by weight to about 25% by weight of said fabric.
 6. The water dispersible fibrous fabric of claim 1, wherein said binder comprises from about 10% by weight to about 20% by weight of said fabric.
 7. The ion-sensitive composition of claim 1, wherein the composition is dispersible in water containing from about 15 ppm to about 150 ppm of one or more divalent and/or multivalent ions.
 8. The ion-sensitive composition of claim 1, wherein the composition is insoluble in a neutral salt solution containing from about 0.3 weight percent to about 5 weight percent salt.
 9. The ion-sensitive composition of claim 1, wherein the polymer is insoluble in a neutral salt solution containing from about 1 weight percent to about 4 weight percent salt.
 10. The ion-sensitive composition of claim 1, wherein the divalent and/or multivalent ions comprise Ca²⁺ ions, Mg²⁺ ions, Zn²⁺ ions, or a combination thereof.
 11. The ion-sensitive composition of claim 1, wherein the monovalent ions comprise Na⁺ ions, Li⁺ ions, K⁺ ions, NH₄ ⁺ ions, or a combination thereof.
 12. The ion-sensitive composition of claim 1, wherein the acrylic acid terpolymer comprises at least one of acrylic acid and methacrylic acid, and one or more alkyl acrylates.
 13. The ion-sensitive composition of claim 1, wherein the sulfonate anion modified acrylic acid terpolymer is formed from at least four monomers selected from acrylic acid; 2-acrylamido-2-methyl-1-propanesulfonic acid and the alkali earth metal and organic amine salts thereof; butyl acrylate; and 2-ethylhexyl acrylate.
 14. The ion-sensitive composition of claim 1, wherein the sulfonate anion modified acrylic acid terpolymer is formed from at least four monomers selected from acrylic acid; AMPS; NaAMPS; butyl acrylate; and 2-ethylhexyl acrylate.
 15. The ion-sensitive composition of claim 1, wherein the sulfonate anion modified acrylic acid terpolymer comprises from about 35 to less than about 80 mole percent acrylic acid; from greater than 0 to about 20 mole percent 2-acrylamido-2-methyl-1-propanesulfonic acid and alkali earth metal and organic amine salts thereof; from greater than 0 to about 65 mole percent butyl acrylate; and from greater than 0 to about 45 mole percent 2-ethylhexyl acrylate.
 16. The ion-sensitive composition of claim 1, wherein the sulfonate anion modified acrylic acid terpolymer comprises from about 50 to less than about 67 mole percent acrylic acid; from greater than 0 to about 10 mole percent 2-acrylamido-2-methyl-1-propanesulfonic acid and alkali earth metal and organic amine salts thereof; from about 15 to about 28 mole percent butyl acrylate; and from about 7 to about 15 mole percent 2-ethylhexyl acrylate.
 17. The ion-sensitive composition of claim 1, wherein the sulfonate anion modified acrylic acid terpolymer comprises from about 57 to less than about 66 mole percent acrylic acid; from about 1 to about 6 mole percent 2-acrylamido-2-methyl-1-propanesulfonic acid and alkali earth metal and organic amine salts thereof; from about 15 to about 28 mole percent butyl acrylate; and from about 7 to about 13 mole percent 2-ethylhexyl acrylate.
 18. The ion-sensitive composition of claim 1, wherein the composition comprises from about 55 to about 95 weight percent of the sulfonate anion modified acrylic acid terpolymer.
 19. The ion-sensitive composition of claim 1, wherein the composition comprises from about 65 to about 80 weight percent of the sulfonate anion modified acrylic acid terpolymer.
 20. The ion-sensitive composition of claim 1, wherein the composition comprises from about 5 to about 45 weight percent of the non-crosslinking poly(ethylene-vinyl acetate).
 21. The ion-sensitive composition of claim 1, wherein the composition comprises from about 20 to about 35 weight percent of the non-crosslinking poly(ethylene-vinyl acetate).
 22. The ion-sensitive composition of claim 1, wherein the sulfonate anion modified acrylic acid terpolymer comprises from about 57 to less than about 66 mole percent acrylic acid; from about 1 to about 6 mole percent AMPS or NaAMPS; from about 15 to about 28 mole percent butyl acrylate; and from about 7 to about 13 mole percent 2-ethylhexyl acrylate; and wherein the composition comprises from about 65 to about 80 weight percent of the sulfonate anion modified acrylic acid terpolymer and from about 20 to about 35 weight percent of the non-crosslinking poly(ethylene-vinyl acetate).
 23. The water dispersible fibrous fabric of claim 1, wherein said fibrous material is a nonwoven fabric.
 24. The water dispersible fibrous fabric of claim 1, wherein said fibrous material will disperse in water after no more than about 60 minutes.
 25. The water dispersible fibrous fabric of claim 1, wherein said fibrous material will disperse in water after no more than about 20 minutes.
 26. The water dispersible fibrous fabric of claim 1, wherein said fibrous material will disperse in water after no more than about 10 minutes.
 27. The water dispersible fibrous fabric of claim 1, wherein after up to about 60 minutes said fibrous material breaks up into multiple pieces each having an average size of less than about 50% relative to its pre-dispersed size.
 28. The water dispersible fibrous fabric of claim 1, wherein after up to about 60 minutes said fibrous material breaks up into multiple pieces each having an average size of less than about 40% relative to its pre-dispersed size.
 29. The water dispersible fibrous fabric of claim 1, wherein after up to about 60 minutes said fibrous material breaks up into multiple pieces each having an average size of less than about 30% relative to its pre-dispersed size.
 30. The water dispersible fibrous fabric of claim 1, wherein said fabric is used in a disposable personal care product.
 31. The water dispersible fibrous fabric of claim 1, wherein said personal care product is selected from a wipe, diaper, training pant, swimwear, absorbent underpant, adult incontinence product, feminine hygiene product, absorbent pad, wound dressing and bandage.
 32. A disposable absorbent article comprising a water dispersible fibrous fabric, wherein the fabric comprises: a fibrous substrate, the fibrous substrate comprising less than about 20% fiber fraction of fibers having a length of about 6-10 mm in length; and a water-dispersible binder comprising a first polymer formed from at least four monomers selected from acrylic acid, 2-acrylamido-2-methyl-1-propanesulfonic acid and alkali earth metal and organic amine salts thereof, butyl acrylate, and 2-ethylhexyl acrylate; and a second polymer comprising a non-crosslinking poly(ethylene-vinyl acetate); wherein the composition is insoluble in a neutral salt solution containing at least about 0.3 weight percent salt, said salt comprising one or more monovalent; wherein said fabric is water dispersible in an aqueous environment containing up to about 200 ppm of one or more multivalent ions and a monovalent ion concentration of less than about 0.5% by weight.
 33. The disposable absorbent article of claim 32, wherein the fibrous substrate is comprised of pulp and synthetic fibers.
 34. The disposable absorbent article of claim 32, wherein the less than about 20% fiber fraction of fibers having a length of about 6-10 mm in length are synthetic fibers.
 35. The disposable absorbent article of claim 32, wherein at least about 80% of the fiber fraction of the fibrous substrate comprises pulp and less than about 20% of the fiber fraction of the fibrous substrate comprises synthetic fibers.
 36. The disposable absorbent article of claim 32, wherein about 85-95% of the fiber fraction of the fibrous substrate comprises pulp and about 5-15% of the fiber fraction of the fibrous substrate comprises synthetic fibers.
 37. The disposable absorbent article of claim 32, wherein about 3-17% of the fibers of the fibrous substrate have a fiber length of about 6-10 mm.
 38. The disposable absorbent article of claim 32, wherein about 5-15% of the fibers of the fibrous substrate have a fiber length of about 6-10 mm.
 39. The disposable absorbent article of claim 32, wherein about 15% of the fibers of fibrous substrate have a length of about 8 mm.
 40. The disposable absorbent article of claim 39, wherein the fibers of fibrous substrate having a length of about 8 mm are synthetic fibers.
 41. The disposable absorbent article of claim 32, wherein said binder comprises less than about 20% by weight of said fibrous fabric and said fibrous substrate comprising more than about 80% by weight of said fibrous fabric.
 42. The disposable absorbent article of claim 32, wherein said binder comprises about 10-15% by weight of said fibrous fabric and said fibrous substrate comprising more than about 85-90% by weight of said fibrous fabric.
 43. The disposable absorbent article of claim 32, wherein the article is a personal care product selected from a wipe, diaper, training pant, swimwear, absorbent underpant, incontinence product, feminine hygiene product, absorbent pad, wound dressing and bandage.
 44. The disposable absorbent article of claim 32, wherein the first polymer of the water-dispersible binder comprises from about 35 to less than about 80 mole percent acrylic acid; from greater than 0 to about 20 mole percent 2-acrylamido-2-methyl-1-propanesulfonic acid and alkali earth metal and organic amine salts thereof; from greater than 0 to about 65 mole percent butyl acrylate; and from greater than 0 to about 45 mole percent 2-ethylhexyl acrylate.
 45. The disposable absorbent article of claim 32, wherein the first polymer of the water-dispersible binder comprises from about 50 to less than about 67 mole percent acrylic acid; from greater than 0 to about 10 mole percent 2-acrylamido-2-methyl-1-propanesulfonic acid and alkali earth metal and organic amine salts thereof; from about 15 to about 28 mole percent butyl acrylate; and from about 7 to about 15 mole percent 2-ethylhexyl acrylate.
 46. The disposable absorbent article of claim 32, wherein the first polymer of the water-dispersible binder comprises from about 57 to less than about 66 mole percent acrylic acid; from about 1 to about 6 mole percent 2-acrylamido-2-methyl-1-propanesulfonic acid and alkali earth metal and organic amine salts thereof; from about 15 to about 28 mole percent butyl acrylate; and from about 7 to about 13 mole percent 2-ethylhexyl acrylate.
 47. The disposable absorbent article of claim 32, wherein the first polymer of the water-dispersible binder is present in an amount from about 55 to about 95 weight percent.
 48. The disposable absorbent article of claim 32, wherein the first polymer of the water-dispersible binder is present in an amount from about 65 to about 80 weight percent.
 49. The disposable absorbent article of claim 32, wherein the second polymer of the water-dispersible binder is present in an amount from about 5 to about 45 weight percent.
 50. The disposable absorbent article of claim 32, wherein the water-dispersible binder comprises from about 20 to about 35 weight percent non-crosslinking poly(ethylene-vinyl acetate).
 51. The disposable absorbent article of claim 32, wherein the first polymer of the water-dispersible binder comprises from about 57 to less than about 66 mole percent acrylic acid; from about 1 to about 6 mole percent AMPS or NaAMPS; from about 15 to about 28 mole percent butyl acrylate; and from about 7 to about 13 mole percent 2-ethylhexyl acrylate; and wherein the composition comprises from about 65 to about 80 weight percent of the first polymer and from about 20 to about 35 weight percent of the second polymer.
 52. A wet wipe comprising: a fibrous substrate, wherein less than about 20% of the fibers comprising the fibrous substrate have a length of about 6-10 mm; and an ion-sensitive water-dispersible binder comprising a sulfonate anion modified acrylic acid terpolymer and a non-crosslinking poly(ethylene-vinyl acetate), wherein the composition is insoluble in a neutral salt solution containing at least about 0.3 weight percent salt, said salt comprising one or more monovalent ions; wherein said binder comprises less than about 25% by weight of said fibrous fabric and said fibrous substrate comprising more than about 75% by weight of said fibrous fabric; wherein the fabric is dispersible in an aqueous environment containing up to about 200 ppm of one or more divalent and/or multivalent ions; and wherein after up to about 60 minutes said fibrous material breaks up into multiple pieces each having an average size of less than about 50% relative to its pre-dispersed size. 